What changed in this filing

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Item 7. Management’s Discussion and Analysis

2025-02-21 compared with 2024-02-16 · 277 added, 236 removed, 390 unchanged (57% of the section changed)

10 unchanged sentences

Alliant Energy takes its responsibility as a corporate citizen seriously and remains a careful steward of the environment and supports the communities in its service territories.

Alliant Energy’s mission and purpose are supported by a strategy focused on meeting the evolving expectations of customers while providing an attractive return for investors, and pursuing emerging technologies and safe, sustainable methods of energy production.

Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, providing an attractive return for investors, and advancing emerging technologies with safe, secure energy production.

This strategy includes the following key elements:

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Providing affordable energy solutions for customers - Alliant Energy’s strategy focuses on affordable energy solutions that support retention and growth of its existing customers and attract new customers to its service territories.

Key Highlights -

• Alliant Energy’s Clean Energy Blueprint, also known as the roadmap for its transition to cleaner energy, continues to add clean energy resources in Iowa and Wisconsin.

• Alliant Energy’s resource plan continues to add resources in Iowa and Wisconsin, which is expected to result in continued reliability and affordability for its utility customers.

As a result, Alliant Energy directly reinvests in the communities it serves through the addition of skilled jobs, economic development and increased tax revenue.

In Wisconsin, WPL completed 639 MW of solar generation in 2023, adding to the 250 MW of solar generation placed in service in 2022, and expects to add another 200 MW of solar generation in 2024, resulting in approximately 1,100 MW of solar generation resources in aggregate.

In Iowa, IPL expects to complete 400 MW of solar generation by the end of 2024.

Completion of these projects is expected to result in approximately 1,500 MW of additional zero-fuel cost solar generation resources for Alliant Energy in aggregate by the end of 2024.

The execution of Alliant Energy’s strategy is expected to result in cost benefits for its utility customers by continuing to add renewable energy projects that generate fuel cost benefits and renewable tax credits that are provided to its electric customers.

• Alliant Energy, IPL and WPL currently expect to utilize various provisions of the Inflation Reduction Act of 2022 to enhance tax benefits expected from wind, solar and battery storage projects in Iowa and Wisconsin, including transferring certain future tax credits from such projects to other corporate taxpayers.

The Inflation Reduction Act of 2022 is expected to result in more cost benefits for IPL’s and WPL’s customers, higher rate base amounts, and improvements in long-term cash flows over the life of the solar, battery storage and wind repowering projects.

Refer to Note 1(c) for discussion of $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2023.

From 2022 through 2024, Alliant Energy completed projects that resulted in approximately 1,500 MW of additional zero-fuel cost solar generation resources in aggregate (WPL completed 1,089 MW of solar generation in Wisconsin in 2022-2024 and IPL completed 400 MW of solar generation in Iowa in 2024), which generate renewable tax credits that are provided to its electric customers.

• Alliant Energy, IPL and WPL have utilized, and expect to continue to utilize, various provisions of the Inflation Reduction Act of 2022 to enhance tax benefits expected from wind, solar and energy storage projects in Iowa and Wisconsin, including transferring certain future tax credits from such projects to other corporate taxpayers.

Refer to Note 1(c) for discussion of $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2024 and 2023, respectively.

• Reductions in Iowa corporate income tax rates resulting from tax reform enacted in 2022 are expected to provide cost benefits to IPL’s electric and gas customers in the future.

• IPL maintaining flat base rates for its retail electric and gas customers in 2021, 2022 and 2023.

• Significant fuel cost reductions achieved in 2021, 2022 and 2023 as a result of shortening the term of IPL’s DAEC PPA by 5 years, and beginning in 2023 with the May 2023 retirement of Lansing.

IPL’s retail electric and gas customers began receiving these benefits with the new base rates effective October 1, 2024.

• IPL maintaining flat base rates for its retail electric and gas customers from 2021 through September 30, 2024, as well as a retail electric base rate moratorium from October 2025 through September 2029 approved by the IUC in IPL’s most recent retail electric rate review.

• Significant fuel cost reductions beginning in 2023 with the completion of various solar facilities.

• Completion of a restructuring and voluntary employee separation program in 2024, which is expected to reduce operation and maintenance expenses in the future.

• Issuance of new long-term debt at historically low interest rates for IPL ($300 million of 3.1% senior debentures due 2051) and WPL ($300 million of 1.95% green bonds due 2031) in 2021 and WPL ($600 million of 3.95% green bonds due 2032) in 2022.

• In 2023, the U.S.

Department of Energy Office of Clean Energy selected the Columbia Energy Storage Project, a first of its kind in the U.S., 20 MW CO2-based long-duration energy storage system at the retiring coal-fired Columbia site, for award negotiations to receive up to $30 million in grant funding.

Alliant Energy, with support from various project partners, currently expects to submit project plans to the PSCW in 2024 after award negotiations with the DOE are finished.

Any grant proceeds would reduce the cost of the project for WPL’s customers.

• Levelized cost recovery mechanism for the remaining net book value of Edgewater Unit 5, which helps reduce customer costs.

Making customer-focused investments - Alliant Energy’s strategic priorities include making significant customer-focused investments toward cleaner and more reliable, resilient, and sustainable customer energy solutions.

• IPL and WPL have entered into conditional commitments with the U.S.

Department of Energy’s Loan Programs Office for loan guarantees of approximately $1.4 billion and $1.6 billion, respectively.

If finalized, such loans would provide low interest financing for IPL’s and WPL’s expected construction of renewable generation and energy storage projects.

• In July 2024, the U.S.

Department of Energy Office of Clean Energy Demonstrations awarded WPL’s Columbia Energy Storage Project, an approximately 20 MW compressed CO2-based long-duration energy storage system at the Columbia Energy Center site, up to approximately $30 million in grant funding during construction of the project.

In addition, in October 2024, the U.S.

Department of Energy Office of Grid Deployment selected WPL’s Smart Power Automation for Rural Communities program application to move into the final stage of award negotiations for up to $50 million in grant funding under the Grid Resilience and Innovation Partnerships Program.

If finalized, any grant proceeds would reduce the cost of the projects for WPL’s customers.

Making customer-focused investments - Alliant Energy’s strategic priorities include making significant customer-focused investments toward more reliable, resilient, and sustainable customer energy solutions.

Alliant Energy’s strategy drives a capital allocation process focused on:

1) transitioning its generation portfolio to meet the growing interest of customers for reliable and sustainable sources of energy, 2) upgrading its electric and gas distribution systems to strengthen safety, reliability and resiliency, as well as enable distributed energy solutions in its service territories, and 3) enhancing its customers’ and employees’ experience with evolving technology and greater flexibility.

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1) transitioning its generation portfolio to meet the growing interest and needs of customers for reliable and sustainable sources of energy, 2) upgrading its electric and gas distribution systems to strengthen safety, reliability and resiliency, as well as enable distributed energy solutions in its service territories, and 3) enhancing its customers’ and employees’ experience with evolving technology and greater flexibility.

Key Highlights (refer to “ Customer Investments ” for details) -

• Development and acquisition of additional renewable energy, including approximately 1,100 MW of solar generation at WPL with in-service dates in 2022-2024, approximately 275 MW of battery storage at WPL with in-service dates in 2024 and 2025, and approximately 400 MW of solar generation at IPL with in-service dates in 2024.

In addition, IPL and WPL continue to evaluate additional opportunities to add more renewable generation, including repowering of existing wind farms and additional solar generation and distributed energy resources, including community solar and small-scale energy storage systems.

• Plans to construct and/or acquire additional renewable, battery and natural gas resources to meet the requirements of MISO’s seasonal resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements effective with the 2023/2024 MISO Planning Year.

• Requested PSCW approval to construct improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs.

A decision from the PSCW is currently expected by the second quarter of 2024.

• Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,200 MW of new wind and solar generation in aggregate, approximately 1,000 MW of energy storage, approximately 750 MW of new natural gas resources, refurbishments at approximately 600 MW of existing wind farms, and improvements at approximately 650 MW of existing natural gas-fired EGUs and the conversion of existing coal-fired EGUs to natural gas.

Alliant Energy is currently evaluating the impact of potential additional large load growth customers and MISO’s seasonal resource adequacy requirements on its resource plans and will update these generation investment plans as needed in the future.

• Completion of new solar generation at WPL (1,089 MW in Wisconsin from 2022-2024) and IPL (400 MW in Iowa in 2024), and IPL’s refurbishment of the existing Franklin County wind farm in Iowa in 2024.

• Improving reliability and resiliency with more underground electric distribution, and enabling distributed energy solutions with higher capacity lines.

Currently, approximately 28% of Alliant Energy’s electric distribution system is underground.

• Alliant Energy continues to partner with its commercial and industrial customers to help develop renewable solutions to enhance their sustainability initiatives, including various customer- and community-hosted solar facilities in Iowa and Wisconsin.

Four such facilities were completed in Wisconsin in 2021 and 2022, and several more are currently planned to be completed in 2024 in Iowa and Wisconsin.

• Alliant Energy continues to partner with its commercial and industrial customers in Iowa and Wisconsin to help develop renewable solutions to support their sustainability initiatives.

• Installing fiber optic routes between Alliant Energy’s facilities to enhance its communications network to improve resiliency and reliability of, and enable and strengthen, the integrated grid network focused on less densely populated rural areas.

Currently, approximately 1,000 miles of underground fiber optic routes have been installed.

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Growing customer demand - Alliant Energy’s strategy supports expanding electric and gas usage in its service territories by promoting electrification initiatives and economic development.

Key Highlights -

• Alliant’s Energy was named a Top Utility in Economic Development by Site Selection Magazine for the fifth year in a row, and was named a Top Utility by Business Facilities Magazine for the fourth year in a row.

• Alliant Energy has various development-ready sites throughout Iowa and Wisconsin, including the 1,300-acre Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the 465-acre Prairie View Industrial Center Super Park in Ames, Iowa, which are rail-served, ready-to-build manufacturing and industrial sites in close proximity to the regional airport, interstate freeways and IPL’s electric services.

The Big Cedar Industrial Center Mega-site also accesses Travero’s rail-served warehouse in Iowa.

In addition, the Beaver Dam Commerce Park is a 520-acre ready-to-build manufacturing and industrial site in Beaver Dam, Wisconsin, with access to commercial and freight airports, interstate freeways and WPL’s electric services.

• The IUC’s order for IPL’s most recent retail electric rate review includes the creation of an individual customer rate tariff, allowing IPL to attract new load growth to its service territory.

In addition, Iowa’s Major Economic Growth Attraction program and Wisconsin’s sales and use tax exemption for qualified data centers, encourage economic development in Alliant Energy’s service territory.

• IPL has entered into electric service agreements with two new customers, who currently expect to build data centers at the Big Cedar Industrial Center in Cedar Rapids, Iowa in IPL’s service territory.

These agreements include aggregate, maximum demands of approximately 1.9 gigawatts.

The electric service agreements are subject to IUC approval under the individual customer rate tariff that was included in the IUC’s September 2024 order for IPL’s retail electric rate review.

The actual timing and amount of increases in IPL’s load are subject to various factors, including interconnections and actual customer demand, and any executed or future agreements with customers are not expected to result in immediate increases in load.

• Various development-ready sites, which are rail-served and in close proximity to a variety of transportation options, are located throughout Alliant Energy’s service territories.

RESULTS OF OPERATIONS

Financial Results Overview - The table below includes EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures.

Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of segment performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.

Financial Results Overview - The table below includes diluted EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures.

Alliant Energy believes these non-GAAP financial measures are useful to investors because they facilitate an understanding of performance and trends, and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.

Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts):

4 unchanged sentences

Alliant Energy Consolidated $690 $2.69 $703 $2.78

Alliant Energy’s Utilities and Corporate Services net income increased by $34 million in 2023 compared to 2022.

The increase was primarily due to higher revenue requirements and AFUDC from capital investments and lower other operation and maintenance expenses at IPL and WPL.

These items were partially offset by higher interest expense, lower retail electric and gas sales primarily due to temperature impacts, and higher depreciation expense.

Alliant Energy’s Non-utility and Parent net income decreased by $23 million in 2023 compared to 2022, primarily due to higher interest expense.

Alliant Energy’s Utilities and Corporate Services net income decreased by $2 million in 2024 compared to 2023.

The decrease was primarily due to an asset valuation charge for IPL’s Lansing Generating Station as a result of the IUC order for IPL’s retail electric rate review, estimated temperature impacts on retail electric and gas sales, restructuring and voluntary separation charges, an ARO charge allocated to the steam business at IPL due to the revised CCR Rule, higher depreciation and financing expenses, and lower AFUDC.

These items were partially offset by higher revenue requirements from capital investments.

Alliant Energy’s Non-utility and Parent net income decreased by $16 million in 2024 compared to 2023, primarily due to higher financing expense.

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6 unchanged sentences

Changes in other utility 2 — 2

Changes in non-utility (3) — —

Changes in total revenues (46) (64) 18

3 unchanged sentences

Changes in cost of gas sold (Refer to details below )

Asset valuation charge for IPL’s Lansing Generating Station in 2024 (Refer to Note 2 for details)

Changes in other operation and maintenance (Refer to details below )

Changes in depreciation and amortization (Refer to Note 2 for discussion of reductions to WPL’s depreciation and amortization expense, which was partially offset by WPL’s solar generation placed in service in 2022)

Changes in depreciation and amortization (Higher primarily due to solar generation placed in service in 2024 and 2023, as well as WPL’s amortization of liquidated damages related to West Riverside procurement contracts, which resulted in reductions to depreciation and amortization expenses in 2023, and updated electric depreciation rates for IPL effective October 1, 2024) (96) (16) (77)

Changes in taxes other than income taxes (7) (3) (4)

2 unchanged sentences

Other income and deductions:

Changes in interest expense (Higher primarily due to financings completed in 2023 and 2022, and higher interest rates) (69) (7) (28)

Changes in equity income from unconsolidated investments, net (Refer to Note 6 for details)

Changes in AFUDC (Higher primarily due to higher levels of CWIP balances related to solar generation and battery storage) 40 10 30

Changes in Other (Refer to Note 13(a) for details of IPL’s qualified pension plan settlement losses in 2022)

Changes in interest expense (Higher primarily due to financings completed in 2024 and 2023) (55) (22) (16)

Changes in AFUDC (Primarily due to changes in levels of CWIP balances related to solar generation and energy storage, and IPL’s refurbishment of the existing Franklin County wind farm) (25) 22 (47)

Changes in Other 6 14 (11)

Changes in total other income and deductions (74) 14 (74)

25 unchanged sentences

$1,625 $1,584 17,489 16,415 $215 $240 102,160 95,222

Sales Trends and Temperatures - Alliant Energy’s retail electric and gas sales volumes decreased 2% and 16%, respectively, in 2023 compared to 2022, primarily due to changes in temperatures.

Estimated increases (decreases) to operating income from the impacts of temperatures were as follows (in millions):

Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes decreased 1% in 2024 compared to 2023, primarily due to changes in sales volumes at IPL’s industrial customers due to standby service customers that can use other generation, and changes in temperatures.

Alliant Energy’s retail gas sales volumes decreased 6% in 2024 compared to 2023, primarily due to changes in temperatures.

Estimated decreases to operating income from the impacts of temperatures were as follows (in millions):

2024 2023 Change 2024 2023 Change

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Alliant Energy IPL WPL

(Lower) higher revenues due to changes in retail electric fuel-related costs (Refer to Electric Production Fuel and Purchased Power Expenses Variances below)

Higher revenue requirements (a)(b) $240 $85 $155

Higher (lower) sales for resale bulk power and other revenues (c) 15 (17) 32

Deferral of incremental solar generation construction costs at WPL in 2024 (Refer to Note 3 )

Lower revenues primarily due to changes in retail electric fuel-related costs at WPL, and credits on IPL’s customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (Refer to Electric Production Fuel and Purchased Power Expenses Variances below) (a)(b)

(142) (42) (100)

Lower sales for resale bulk power and other revenues (a) (40) (2) (38)

Lower wholesale revenues primarily due to lower fuel-related costs (20) (2) (18)

Estimated changes in sales volumes caused by temperatures (32) (17) (15)

Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric production fuel and purchased power expenses) (Refer to Note 2 )

Higher revenues at IPL related to changes in the electric transmission service cost rider (mostly offset in electric transmission service expense) (Refer to Electric Transmission Service Expense Variances below)

Higher revenues at IPL related to changes in the renewable energy rider (mostly offset by changes in income taxes) 13 13 —

Changes in WPL electric fuel-related costs, net of recoveries (b) 12 — 12

Other (15) (13) (2)

Estimated changes in sales volumes caused by temperatures (23) (13) (10)

Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider in 2024 (partially offset by changes in income taxes) (a) (16) (16) —

Lower wholesale revenues at WPL primarily due to lower fuel-related costs and lower sales (13) (1) (12)

Lower revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) )

Changes in WPL electric fuel-related costs, net of recoveries (d) (10) — (10)

$27 ($14) $41

(a) Alliant Energy’s sales for resale bulk power and other revenues decreased primarily due to lower prices for electricity sold by IPL and WPL to MISO wholesale energy markets.

(a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $185 million for IPL’s retail electric customers, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, for the October 2024 through September 2025 forward-looking Test Period.

Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing electric rate base including investments in solar generation, updated depreciation rates, and certain incremental costs incurred resulting from the 2020 derecho windstorm.

In addition, effective October 1, 2024, IPL’s renewable energy rider was discontinued, and certain production tax credits are credited to IPL’s retail electric customers through IPL’s fuel-related cost recovery mechanism.

Credits on IPL’s customers’ bills are expected to be offset by a reduction in income tax expense.

(b) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $49 million for WPL’s retail electric customers, covering the 2024 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base and lower forecasted fuel-related expenses.

(c) Alliant Energy’s and WPL’s sales for resale bulk power and other revenues increased primarily due to higher volumes and higher prices for electricity sold by WPL to MISO wholesale energy markets.

Alliant Energy’s increase was partially offset by decreased sales for resale bulk power and other revenues at IPL primarily due to lower prices for electricity and capacity sold by IPL to MISO wholesale energy markets.

These changes were largely offset by changes in fuel-related costs.

(b) WPL’s cost recovery mechanism for retail fuel-related expenses supports deferrals of amounts that fall outside an approved fuel monitoring range of forecasted fuel-related expenses determined by the PSCW each year.

(d) WPL’s cost recovery mechanism for retail fuel-related expenses supports deferrals of amounts that fall outside an approved fuel monitoring range of forecasted fuel-related expenses determined by the PSCW each year.

The difference between revenue collected and actual fuel-related expenses incurred within the fuel monitoring range increases or decreases Alliant Energy’s and WPL’s electric utility revenues.

WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately ($4) million and $6 million in 2024 and 2023, respectively.

Refer to Note 2 for discussion of deferred fuel-related costs that were outside the approved fuel monitoring range in 2023, 2022 and 2021.

Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for 2024 compared to 2023 (in millions):

3 unchanged sentences

Estimated changes in sales volumes caused by temperatures (8) (4) (4)

Higher revenue requirements at WPL (a) 8 — 8

Higher revenues at IPL related to changes in recovery amounts for energy efficiency costs through the energy efficiency rider (mostly offset by changes in energy efficiency expense) (Refer to Note 1(g) )

Other (3) (1) (2)

Higher revenue requirements (a) (b) 14 2 12

($75) ($50) ($25)

(a) In December 2022, the PSCW issued an order authorizing an annual base rate increase of $9 million for WPL’s retail gas customers, covering the 2023 forward-looking Test Period, which reflects changes in weighted average cost of capital, updated depreciation rates and modifications to certain regulatory asset and regulatory liability amortizations.

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(a) In September 2024, the IUC issued an order authorizing an annual base rate increase of $10 million for IPL’s retail gas customers, for the October 2024 through September 2025 forward-looking Test Period.

Rate changes were effective October 1, 2024, which reflect revenue requirement impacts of increasing gas rate base.

(b) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $13 million for WPL’s retail gas customers, covering the 2024 forward-looking Test Period, which reflects revenue requirement impacts of increasing gas rate base.

Electric Production Fuel and Purchased Power Expenses Variances - The following items contributed to (increased) decreased electric production fuel and purchased power expenses for 2024 compared to 2023 (in millions):

1 unchanged sentence

Lower electric production fuel costs (a) $108 $72 $36

Lower purchased power expense (b) 152 7 145

Changes in regulatory recovery of retail electric fuel-related costs (Refer to Notes 1(g) and 2 )

(109) 42 (151)

Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric utility revenue) (Refer to Note 2 )

$94 $101 ($8)

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(a) Electric production fuel costs decreased primarily due to lower natural gas prices in 2023 compared to 2022 and lower coal volumes utilized due to IPL’s retirement of Lansing in May 2023, partially offset by higher natural gas volumes due to higher dispatch of IPL’s and WPL’s natural gas-fired EGUs in 2023.

(b) Purchased power expense decreased primarily due to lower prices for electricity purchased by IPL and WPL from MISO wholesale energy markets, and decreased volumes of electricity purchased due to lower retail and wholesale electric sales and less reliance on wholesale energy market purchases due to higher dispatch of IPL’s and WPL’s natural gas-fired EGUs.

Changes in regulatory recovery of retail electric fuel-related costs (Refer to Note 1(g) )

Higher purchased power expense (b) (49) (38) (11)

Other (5) — (4)

(a) Electric production fuel costs decreased at IPL primarily due to lower natural gas prices in 2024 compared to 2023, and lower natural gas and coal volumes due to lower dispatch of IPL’s EGUs in 2024.

Electric production fuel costs decreased at WPL primarily due to lower natural gas prices in 2024 compared to 2023, and higher dispatch of WPL’s renewable EGUs in 2024, partially offset by higher coal volumes due to higher dispatch of WPL’s coal-fired EGU’s in 2024.

(b) Purchased power expense increased primarily due to higher prices for electricity purchased by IPL and WPL, and higher volumes of electricity purchased at IPL due to lower dispatch of IPL’s EGUs in 2024, partially offset by lower volumes of electricity purchased at WPL due to higher dispatch of WPL’s EGUs in 2024.

Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for 2024 compared to 2023 (in millions):

2 unchanged sentences

($28) ($7) ($21)

Other (primarily due to changes in transmission service costs provided by third parties) (2) 10 (12)

($30) $3 ($33)

1 unchanged sentence

Alliant Energy IPL WPL

Lower natural gas prices and lower retail gas volumes primarily due to changes in temperatures $77 $24 $53

Lower natural gas prices and lower retail gas volumes $105 $66 $39

Changes in the regulatory recovery of gas costs (Refer to Note 1(g ) )

Other (1) (2) —

(30) (24) (6)

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2024 compared to 2023 (in millions):

Alliant Energy IPL WPL

Lower incentive compensation expense $7 $4 $3

Non-utility Travero (mostly offset by lower non-utility revenues) 4 — —

Higher energy efficiency expense at IPL (mostly offset by higher revenues) (5) (5) —

Lower (higher) generation and energy delivery expenses (1) 5 (6)

Other (includes lower costs due to cost controls and operational efficiencies) 24 12 10

Restructuring and voluntary employee separation charges in 2024 (excluding payroll taxes) (Refer to Note 12(a) )

($27) ($13) ($12)

ARO charge for steam assets at IPL in 2024 (Refer to Note 13 )

Lower energy efficiency expense at IPL (mostly offset by lower revenues) 20 20 —

Lower generation and energy delivery expenses 11 3 8

Other 15 5 (4)

($1) ($5) ($8)

Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:

• Financing Plans - Alliant Energy currently expects to issue up to $25 million of common stock in 2025 through its Shareowner Direct Plan.

IPL, WPL and AEF currently expect to issue up to $700 million, $300 million and $700 million of long-term debt, respectively, in 2024.

IPL and AEF have $500 million and $300 million of long-term debt, respectively, maturing in 2024.

In 2025, IPL currently expects to issue up to $600 million of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $600 million of long-term debt in aggregate.

IPL and AEF each have $300 million of long-term debt maturing in 2025.

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• Common Stock Dividends - Alliant Energy announced a 6% increase in its targeted 2025 annual common stock dividend to $2.03 per share, which is equivalent to a quarterly rate of $0.5075 per share, beginning with the February 2025 dividend payment.

The timing and amount of future dividends is subject to an approved dividend declaration from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.

The timing and amount of future dividends is subject to approval of quarterly dividend declarations from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.

• Cash Flows From Operating Activities - Alliant Energy, IPL and WPL currently expect an increase in future cash flows from operating activities resulting from the transfer of future renewable tax credits to other corporate taxpayers pursuant to the Inflation Reduction Act of 2022.

In addition, Alliant Energy and WPL currently expect an increase in future cash flows from operating activities resulting from higher earnings on increasing rate base at WPL.

• IPL’s Electric Sales Trends - In July 2025, IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative will expire.

Sales to Southern Minnesota Energy Cooperative represented approximately 5% of IPL's total electric sales in 2023.

• Higher Earnings on Increasing Rate Base - Alliant Energy and WPL currently expect an increase in earnings in 2024 compared to 2023 due to impacts from increasing revenue requirements related to investments in the utility business.

• Depreciation and Amortization Expense - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expense in 2024 compared to 2023 due to capital projects placed in service in 2023 and 2024 and lower amortization of WPL’s West Riverside liquidated damages.

Refer to Note 2 for discussion of WPL’s West Riverside liquidated damages.

In addition, Alliant Energy, IPL and WPL currently expect an increase in future cash flows from operating activities resulting from higher earnings on increasing rate base at IPL and WPL.

• Higher Earnings on Increasing Rate Base - Alliant Energy, IPL and WPL currently expect increases in electric utility and gas utility revenues in 2025 compared to 2024 due to impacts from increasing revenue requirements related to investments in the utility business.

In addition, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2025 compared to 2024 due to additional tax credits from renewable generation and energy storage projects placed in service in 2024 and/or expected to be placed in service in 2025.

A majority of the differences between actual renewable tax credits and renewable tax credits used to determine rates are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers.

Investment tax credits resulting from IPL energy storage projects expected to be placed in service in 2025 may be utilized to offset any revenue deficiency on an annual basis up to the earnings sharing mechanism threshold included in IPL’s retail electric rate review settlement agreement discussed in “ Rate Matters .”

• Sales Trends and Temperatures - In July 2025, IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative (SMEC) will expire (sales to SMEC represented approximately 5% of IPL’s total electric sales in 2024), which is not expected to have a material impact on Alliant Energy’s or IPL’s future financial condition and results of operations.

In 2024, warmer than normal temperatures in the winter and cooler than normal temperatures in the summer in Alliant Energy’s, IPL’s and WPL’s service territories resulted in lower retail electric and gas sales volumes and operating income.

• Other Operation and Maintenance Expenses - Alliant Energy, IPL and WPL currently expect a decrease in other operation and maintenance expenses in 2025 compared to 2024 largely due to the asset valuation charge for IPL’s Lansing Generating Station and ARO charge for steam assets at IPL recorded in 2024, charges for restructuring and voluntary employee separation recorded in 2024, as well as expected future cost savings related to Alliant Energy’s restructuring activities.

These items are expected to be partially offset by higher generation maintenance and energy delivery expenses.

• Depreciation and Amortization Expense - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expense in 2025 compared to 2024 due to capital projects placed in service in 2024 and 2025, and updated electric depreciation rates for IPL effective October 1, 2024.

• Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2025 compared to 2024 due to financings completed in 2024 and planned in 2025 as discussed above.

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• AFUDC - Alliant Energy and WPL currently expect a decrease and IPL currently expects an increase in AFUDC in 2024 compared to 2023 largely due to changes in CWIP balances related to construction activity on capital projects.

CUSTOMER INVESTMENTS

Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward cleaner energy and more reliable, resilient and sustainable customer solutions.

Alliant Energy’s, IPL’s and WPL’s strategic priorities include making significant customer-focused investments toward reliable, resilient and sustainable customer energy solutions.

These priorities include:

Clean Energy Blueprint

Alliant Energy has developed a Clean Energy Blueprint, or the roadmap for its transition to cleaner energy, as a guide to meet customer demand for affordable, safe, reliable and sustainable energy in Iowa and Wisconsin.

This strategy includes the development and acquisition of additional renewable energy, including approximately 1,100 MW of solar generation at WPL with in-service dates in 2022-2024, approximately 275 MW of battery storage at WPL with in-service dates in 2024 and 2025, and approximately 400 MW of solar generation at IPL with in-service dates in 2024.

In order to support reliable and sustainable energy and meet MISO’s seasonal resource adequacy requirements, Alliant Energy, IPL and WPL continue to evaluate additional opportunities for renewables and battery storage projects, dispatchable gas generation projects, and distributed energy resources, as well as repowering existing wind farms.

Estimated capital expenditures for these planned projects for 2024 through 2027 are included in the “Renewables and battery storage projects” line in the construction and acquisition table in “ Liquidity and Capital Resources .”

WPL’s Generation Projects - In 2021 and 2022, WPL received orders from the PSCW for its first and second solar CAs authorizing WPL to acquire, construct, own, and/or operate 675 MW and 414 MW, respectively, of new solar generation in various Wisconsin counties.

In 2022 and 2023, 250 MW and 639 MW of solar projects were placed in service, respectively, and a 200 MW solar project is expected to be placed in service in 2024.

The 1,089 MW of new solar generation is expected to help replace energy and capacity being eliminated with the planned retirements of the coal-fired Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 (595 MW in aggregate) by June 1, 2026, which are the last coal-fired EGUs at WPL.

In June 2023, WPL filed requests with the PSCW for approval to construct improvements at the natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs.

A decision from the PSCW is currently expected by the second quarter of 2024.

In August 2023, WPL received an order from the PSCW authorizing WPL to construct, own and operate 175 MW of battery storage, with 100 MW and 75 MW at the Grant County and Wood County solar projects, respectively, which are currently expected to be placed in service in 2024.

In December 2023, WPL received an order from the PSCW authorizing WPL to construct, own and operate approximately 99 MW of battery storage at the Edgewater Generating Station, which is currently expected to be placed in service in 2025.

IPL’s Generation Projects - In October 2023, the IUB issued an order approving a modified non-unanimous settlement agreement with the Iowa Office of Consumer Advocate among other stakeholders, for advance rate-making principles for up to 400 MW of solar generation, subject to a cost target of $1,650/kilowatt, including AFUDC and transmission upgrade costs among other costs, and a related return on common equity of no less than 10.25% with the opportunity to request a higher return on common equity in future IPL retail electric rate review filings.

Any reasonable and prudent costs incurred in excess of the cost target are eligible for recovery at the return on common equity determined in IPL retail electric rate review filings.

The IUB’s order also included a consumer protection plan, which monitors IPL’s achievement of certain aggregate summer capacity factors for the up to 400 MW of solar generation projects during June, July and August each calendar year over 30 years.

Actual three-year rolling average summer capacity factors will be compared to target capacity factors, which may result in surpluses or deficits that would be offset against one another and contribute to an accumulated balance in a given calendar year.

Surpluses or deficits will be capped at $3 million in aggregate per year.

At the end of the program, any accumulated deficit balance would be addressed in IPL’s next rate review, and any accumulated surplus balance would not result in any return to IPL.

In November 2023, IPL accepted these advance rate-making principles.

In 2023, the IUB issued GCU Certificates granting IPL approval to construct, own and operate up to 150 MW of solar generation at the Wever project in Lee County, Iowa and up to 50 MW of solar generation at the Creston project in Union County, Iowa.

These solar projects are included in the IUB’s October 2023 order approving advance rate-making principles for up to 400 MW of solar generation.

The IUB also issued GCU Certificates granting IPL approval to construct, own and operate up to 100 MW of battery storage (75 MW at the Wever project and 25 MW at the Creston project), which was not included in the IUB’s October 2023 order approving advance rate-making principles, and is subject to future regulatory approval.

The 400 MW of new solar generation would help replace a portion of the energy and capacity eliminated with the May 2023 retirement of the coal-fired Lansing Generating Station (275 MW) and the reduction of energy and capacity resulting from the December 2021 fuel switch of the Burlington Generating Station (212 MW) from coal to natural gas.

In addition, IPL’s plans include additional renewables and distributed energy resources, including community solar and small-scale energy storage systems, and repowering existing wind farms, to add energy and capacity.

Resource Planning

Alliant Energy’s current resource plan continues to add resources in Iowa and Wisconsin, and serves as a guide to meet customer demand for affordable, safe, reliable and sustainable energy.

Over the next five years, Alliant Energy currently plans to develop and/or acquire new generation investments to add flexibility with evolving load growth, including approximately 1,200 MW of new wind and solar generation in aggregate, approximately 1,000 MW of energy storage, approximately 750 MW of new natural gas resources, refurbishments at approximately 600 MW of existing wind farms, and improvements at approximately 650 MW of existing natural gas-fired EGUs and the conversion of existing coal-fired EGUs to natural gas.

Estimated capital expenditures for these planned projects for 2025 through 2028 are included in the “Generation” section in the construction and acquisition table in “ Liquidity and Capital Resources .” Information on IPL’s and WPL’s regulatory filings and/or approvals for future generation and energy storage projects, as well as recently completed projects, are as follows:

WPL’s Generation and Energy Storage Projects -

Solar - In 2022 through 2024, WPL completed 1,089 MW of new solar generation projects in Wisconsin, including the Grant County facility (200 MW) in 2024.

Refer to Note 3 for discussion of the construction costs associated with these projects.

Energy Storage - In 2023, the PSCW issued orders authorizing WPL to construct, own and operate energy storage at the Grant County (100 MW) and Wood County (75 MW) solar projects in Wisconsin, which is currently expected to be placed in service in the second half of 2025, and at the Edgewater Generation Station in Wisconsin (approximately 99 MW), which is currently expected to be placed in service in 2026.

In July 2024, the U.S.

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Energy Center site, up to approximately $30 million in grant funding during construction of the project.

In August 2024, WPL filed a CA application with the PSCW for construction approval of the energy storage system.

A decision from the PSCW is currently expected in the second quarter of 2025.

If finalized, any grant proceeds would reduce the cost of the project for WPL’s customers.

Existing Natural Gas-Fired Electric Generating Unit Improvements - In April 2024, the PSCW issued orders authorizing WPL to construct improvements at the existing natural gas-fired Neenah Energy Facility and Sheboygan Falls Energy Facility, which would increase the capacity and efficiency of the EGUs.

Existing Wind Farm Refurbishment - In July 2024, WPL filed a CA application with the PSCW for approval to refurbish the Bent Tree wind farm, which would be eligible for production tax credits under the Inflation Reduction Act of 2022.

A decision from the PSCW is currently expected in the first quarter of 2025.

IPL’s Generation and Energy Storage Projects -

Solar - In 2024, IPL completed new solar generation projects in Iowa, including the Wever facility (150 MW), the Creston facility (50 MW), and the first (50 MW) and second (150 MW) phases of the Pleasant Creek facility.

Refer to Note 3 for discussion of the construction costs associated with these projects.

Energy Storage - IPL received approval from the IUC to construct, own and operate up to approximately 140 MW of energy storage in Iowa (100 MW at the Wever project and 40 MW at the Creston project), which is currently expected to be placed in service in 2025 and 2026.

Natural Gas-fired Electric Generating Unit - In February 2025, IPL filed request with the IUC for approval to construct, own and operate the Cedar River Generating Station, a 94 MW natural gas-fired EGU using Reciprocating Internal Combustion Engine (RICE) technology, at the site of IPL’s Prairie Creek Generation Station.

A decision from the IUC is currently expected in the fourth quarter of 2025.

Existing Wind Farm Refurbishment - In 2024, IPL completed the refurbishment of the existing Franklin County wind farm in Iowa.

IPL currently expects the refurbishment of the existing Whispering Willow - East wind farm to be completed in 2026.

These projects are eligible for production tax credits under the Inflation Reduction Act of 2022.

WPL’s West Riverside Natural Gas-fired Generating Station - In 2020, WPL completed the construction of West Riverside, a 723 MW natural gas-fired combined-cycle EGU in Beloit, Wisconsin.

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WEC Energy Group, Inc.

(WEC) 100 MW were acquired by WEC in June 2023 pursuant to PSCW and FERC approval;

additionally, WEC exercised its second and final option to purchase an additional 100 MW, subject to PSCW and FERC approval (a)

Madison Gas and Electric Company (MGE) 25 MW were acquired by MGE in March 2023 pursuant to PSCW and FERC approval;

additionally, MGE exercised its second and final option to purchase an additional 25 MW, subject to PSCW and FERC approval

Electric cooperatives Approximately 60 MW were acquired January 2018

(a) Upon WEC’s exercise of its options, WPL may exercise reciprocal options, subject to approval by the PSCW, to purchase up to 200 MW of any natural-gas combined-cycle EGU that WEC places in service prior to May 2030.

(WEC) In 2023 and 2024, WEC acquired 200 MW in aggregate, pursuant to PSCW and FERC approval (a)

Madison Gas and Electric Company (MGE) In 2023 and 2024, MGE acquired 50 MW in aggregate, pursuant to PSCW and FERC approval

Electric cooperatives Approximately 60 MW were acquired in 2018

(a) WPL may exercise reciprocal options, subject to approval by the PSCW, to purchase up to 200 MW of any natural-gas combined-cycle EGU that WEC places in service prior to May 2030.

Plant Retirements and Fuel Switching - The current strategy includes the retirement, or fuel switch from coal to natural gas, of various EGUs in the next several years.

IPL retired the coal-fired Lansing Generating Station (275 MW) in May 2023, and currently expects to fuel switch or retire Prairie Creek Units 1 and 3 (65 MW in aggregate) by December 31, 2025.

WPL currently expects to retire the coal-fired Edgewater Generating Station (414 MW) by June 1, 2025, and Columbia Units 1 and 2 (595 MW in aggregate) by June 1, 2026.

IPL currently expects to retire Prairie Creek Unit 1 and fuel switch Prairie Creek Unit 3 (65 MW in aggregate) by December 31, 2025.

WPL currently expects to convert the coal-fired Edgewater Unit 5 (414 MW) to natural gas in 2028.

In addition, WPL currently plans to cease coal operations at Columbia Units 1 and 2 (595 MW in aggregate) by the end of 2029, as well as evaluate the conversion of Columbia Unit 1 and/or Unit 2 to natural gas.

Alliant Energy, IPL and WPL are working with MISO, state regulatory commissions and other regulatory agencies, as required, to determine the timing of these actions, which are subject to change depending on operational, regulatory, market and other factors.

Refer to Note 3 for additional details on these EGUs.

Environmental Stewardship - Alliant Energy’s environmental stewardship is focused on meeting its customers’ energy needs affordably, safely, reliably and sustainably.

Alliant Energy proactively considers future environmental compliance requirements and proposed regulations in its planning, decision-making, construction and ongoing operations activities.

Alliant Energy is focused on executing a long-term strategy to deliver reliable and affordable energy with lower emissions independent of changing policies and political landscape.

To achieve these long-term goals, Alliant Energy will transition away from coal-fired EGUs by incorporating renewable energy, distributed energy resources, energy efficiency, demand response, natural gas-fired EGUs and other technologies such as energy storage.

Refer to Note 3 for additional details on Columbia Units 1 and 2, and Edgewater Unit 5.

Environmental Stewardship - Alliant Energy’s environmental stewardship is focused on the implementation of a responsible energy strategy to meet its customers’ energy needs affordably, safely, reliably and sustainably.

Alliant Energy periodically reviews and updates this strategy to reflect changes needed to support the transition to a low-carbon economy.

Alliant Energy’s current voluntary environmental-related goals and achievements include the following:

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• By 2030, reduce GHG emissions from its utility operations by 50% from 2005 levels, reduce its electric utility water supply by 75% from 2005 levels and electrify 100% of its owned light-duty fleet vehicles.

• By 2040, eliminate all coal-fired EGUs from its generating fleet and reduce GHG emissions from its utility operations by 80% from 2005 levels.

• By 2040, eliminate all coal-fired EGUs from its generating fleet.

• By 2050, aspire to achieve net-zero GHG emissions from its utility operations.

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Alliant Energy’s aspirational GHG goal includes EPA reportable emissions based on applicable regulatory compliance requirements for CO2, methane and nitrous oxide from its owned fossil-fueled EGUs and distribution of natural gas.

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Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2025 through 2028 are included in the “Electric and gas distribution systems” lines in the construction and acquisition expenditures table in “ Liquidity and Capital Resources .”

Grid Resilience and Innovation Partnerships Program for WPL - In October 2024, the U.S.

WPL currently expects to submit project plans to the PSCW in 2025 when award negotiations are nearing completion.

If finalized, any grant proceeds would reduce the cost of the project for WPL’s customers.

Fiber Optic Telecommunication Network - Alliant Energy is currently installing fiber optic routes between its facilities to enhance its communications network to improve resiliency and reliability of, and enable and strengthen, the integrated grid network focused on less densely populated rural areas.

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Gas Pipeline Expansion - IPL and WPL currently expect to make investments to extend various gas distribution systems to provide natural gas to unserved or underserved areas in their service territories.

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Plans to address certain requirements for specific pipelines were developed and implemented, with identified remediation efforts to be completed by July 2035.

In anticipation of these rule changes, Alliant Energy, IPL and WPL have been proactively replacing certain of IPL’s transmission pipelines, making modifications to certain of WPL’s transmission pipelines, and updating practices for assessment and operation of these pipelines.

In response to these rule changes, Alliant Energy, IPL and WPL have been assessing, testing and modifying certain of IPL’s and WPL’s pipelines, and updating practices for assessment and operation of all IPL and WPL pipelines.

Alliant Energy, IPL, and WPL also continue to evaluate the impact of these final rules and resulting remediation plans on their financial condition and results of operations.

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Given that a portion of the rate changes will offset changes in costs, revenues from rate changes should not be expected to result in an equal change in net income for either IPL or WPL.

IPL’s Retail Electric and Gas Rate Reviews (October 2024 Through September 2025 Forward-looking Test Period) - In September 2024, the IUC issued an order for IPL’s retail electric and gas rate reviews for the October 2024 through September 2025 forward-looking Test Period with rate changes effective October 1, 2024.

Key drivers for the rate review included revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation, as well as updated depreciation rates and certain incremental costs incurred resulting from the 2020 derecho windstorm.

The IUC’s order included the following provisions:

• Annual retail electric base rate increase of $185 million, with customers receiving partially offsetting credits for the first 12 months through a tax benefit rider, and a subsequent retail electric base rate moratorium through September 2029;

• During the moratorium, IPL may request updated rates if its actual return on common equity is 100 or more basis points below the authorized return on common equity for a single calendar year or 50 or more basis points below the authorized return on common equity for two consecutive years, and/or if a material change in laws or regulations causes the moratorium to become unsustainable;

• Annual retail gas base rate increase of $10 million;

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• Electric earnings sharing mechanism beginning in calendar year 2025, where IPL would apply excess earnings to the remaining net book value of IPL’s highest earning asset with advance ratemaking principles (currently the Emery Generation Station) based on its authorized return on common equity as follows;

Threshold Above Authorized

Return on Common Equity Sharing

First 50 basis points 75% customers, 25% IPL

>50 to 100 basis points 50% customers, 50% IPL

>100 to 150 basis points 25% customers, 75% IPL

>150 basis points 100% customers

• Investment tax credits resulting from renewable generation and energy storage projects may be utilized to offset any revenue deficiency on an annual basis up to IPL’s return on common equity threshold;

any remaining investment tax credits, net of the cost of transferability, that are not used to offset any revenue deficiency, will be deferred by IPL and carried forward to offset any revenue deficiency in future years;

• Creation of an individual customer rate tariff, which would allow IPL to attract new load growth to its service territory;

• Electric distribution system investment cap not to exceed $900 million in aggregate or $325 million in any given year from 2026 through 2029, with certain exceptions;

• IPL to retain renewable production tax credits from new generation resources not included in base rates and the repowering of existing wind farms, including the Franklin County wind farm refurbishment, as well as retain energy margins for new generation resources and energy storage;

• Discontinuation of the renewable energy rider;

• A return of the remaining net book value of the Lansing Generating Station;

however, the IUC’s order does not include a return on the remaining net book value of Lansing, resulting in Alliant Energy and IPL recording a pre-tax non-cash charge of $60 million to “Asset valuation charge for IPL’s Lansing Generating Station” in their income statements in 2024.

WPL’s Retail Electric and Gas Rate Reviews (2024/2025 Forward-looking Test Period) - In December 2023, the PSCW issued an order authorizing annual base rate increases of $49 million and $13 million for WPL’s retail electric and gas customers, respectively, effective January 1, 2024, for the 2024 forward-looking Test Period.

The PSCW’s order also authorized WPL to implement an additional $60 million increase in annual rates for its retail electric customers, effective January 1, 2025, for the 2025 forward-looking Test Period.

The key drivers for the annual base rate increases include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and battery storage.

The key drivers for the annual base rate increases include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and energy storage.

The order extends, with certain modifications, an earnings sharing mechanism through 2025.

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WPL must defer 50% of its excess earnings between 9.95% and 10.55%, and 100% of any excess earnings above 10.55%.

The PSCW also authorized WPL to defer the incremental under-/over-collection of solar and battery storage renewable tax credits that are outside of the approved amounts.

In addition, the PSCW authorized continued recovery of and a return on the remaining net book value of Edgewater Unit 5, which is currently expected to be retired by June 1, 2025.

Refer to N ote 3 for details of the PSCW’s February 2024 oral decision approving WPL’s deferral request to seek recovery of solar generation construction costs that exceed amounts previously approved by the PSCW in a future regulatory proceeding.

IPL’s Retail Electric and Gas Rate Reviews (October 2024 Through September 2025 Forward-looking Test Period) - In October 2023, IPL filed a retail electric and gas rate review with the IUB for the October 2024 through September 2025 forward-looking Test Period.

The key drivers for the filing include revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation and repowering of the existing Franklin County wind farm, as well as certain incremental costs and benefits incurred resulting from the 2020 derecho windstorm.

The filing requested approval for IPL to implement increases in annual rates for its retail electric and gas customers of $160 million and $14 million, respectively, with any granted rate changes expected to be effective on October 1, 2024.

IPL’s filing also requested approval to implement an additional $124 million increase in annual rates for its retail electric customers in 2025, with any granted rate changes expected to be effective on October 1, 2025.

IPL also requested a return on common equity of 10% and a 52% common equity component of its regulatory capital structure, as well as to receive continued recovery of and a return on the remaining net book value of the Lansing Generating Station through 2037, which was retired in May 2023.

A decision from the IUB is currently expected in the third quarter of 2024.

WPL’s Retail Fuel-related Rate Filing (2022 Forward-looking Test Period) - In August 2023, the PSCW authorized WPL to collect $117 million in higher rates, plus interest, from its retail electric customers from October 2023 through December 2025 for fuel-related costs incurred by WPL in 2022 that were higher than fuel-related costs used to determine rates for such period.

WPL’s Retail Fuel-related Rate Filing (2023 Forward-looking Test Period) - In December 2022, the PSCW authorized WPL to collect $47 million in higher rates in 2023 from its retail electric customers to reflect an increase in expected fuel-related costs for 2023 compared to WPL’s approved 2022 fuel-related costs.

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The PSCW also authorized WPL to defer the incremental under-/over-collection of solar and energy storage renewable tax credits that are different than the approved amounts.

Refer to N ote 3 for discussion of the PSCW’s 2024 orders related to the deferral of, and deferral of a return on, incremental solar generation construction costs in 2024 and 2025.

WPL’s Retail Fuel-related Rate Filing (2023 Forward-looking Test Period) - In August 2024, the PSCW issued an order authorizing WPL to refund $34 million, plus interest, to its retail electric customers in 2024 for fuel-related costs incurred by WPL in 2023 that were lower than fuel-related costs used to determine rates for such period.

Rate Review Details - Details related to IPL’s and WPL’s key jurisdictions were as follows:

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Body (in millions) Equity (a) Capital Structure Date

IPL Retail Electric (2020 Test Period)

Marshalltown (b) IUB $559 11.00% 51.0% 2/26/2020

Emery (b) IUB 165 12.23% 51.0% 2/26/2020

Whispering Willow - East (b) IUB 163 11.70% 51.0% 2/26/2020

Renewable energy rider (c) IUB 1,491 9.80% 51.0% 1/1/2024

Other (b) IUB 3,767 9.50% 51.0% 2/26/2020

IPL Retail Gas (2020 Test Period) (b) IUB 557 9.60% 51.0% 1/10/2020

IPL Retail Electric (October 2024-September 2025 Test Period) (b)

Marshalltown IUC $484 11.00% 51.0% 10/1/2024

Emery IUC 90 12.23% 51.0% 10/1/2024

Whispering Willow - East IUC 124 11.70% 51.0% 10/1/2024

Wind IUC 1,218 11.00% 51.0% 10/1/2024

Solar IUC 511 10.25% 51.0% 10/1/2024

Other (c) IUC 4,852 9.34% 51.0% 10/1/2024

IPL Retail Gas (October 2024-September 2025 Test Period) (b) IUC 630 9.65% 51.0% 10/1/2024

IPL Wholesale Electric FERC 170 10.97% 50.0% 1/1/2024

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(a) Authorized returns on common equity may not be indicative of actual returns earned or projections of future returns.

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(b) Average rate base amounts reflect IPL’s allocated retail share of rate base and do not include CWIP and were calculated using a forecasted 13-month average for the test period.

(c) Average rate base amounts recovered through IPL’s renewable energy rider mechanism include construction costs incurred to fund IPL’s 1,000 MW of wind generation facilities placed in service in 2019 and 2020 (11.00% return on common equity), production tax credit carryforwards for the 1,000 MW of wind generation facilities (5.00% return on common equity) and certain transmission facilities classified as intangible assets (9.50% return on common equity), and were calculated using a 13-month average.

(c) Average rate base amounts include assets that do not have advance rate-making principles (9.65% return on common equity), production tax credits carryforwards for 1,000 MW of wind generating facilities placed in service in 2019 and 2020 (5% return on common equity), as well as the portion of Whispering Willow - East that does not earn a return on investment.

(d) Average rate base amounts reflect WPL’s allocated retail share of rate base and do not include CWIP or a cash working capital allowance, and were calculated using a forecasted 13-month average for the test period.

The PSCW provides a return on selected CWIP and a cash working capital allowance by adjusting the percentage return on rate base.

Planned Rate Review - WPL currently expects to file a retail electric and gas rate review with the PSCW by the end of the second quarter of 2025 for the 2026/2027 forward-looking Test Period.

The key drivers for the anticipated filing include revenue requirement impacts of increasing electric and gas rate base.

Any rate changes granted from this pending request are expected to be effective on January 1, 2026, with a decision from the PSCW expected by the end of 2025.

LEGISLATIVE MATTERS

In May 2024, the Major Economic Growth Attraction program was enacted in Iowa, which offers various tax incentives for up to two qualified businesses for certain large-scale projects with capital investments greater than $1 billion constructed on certified sites greater than 250 acres in Iowa.

The most significant provision of this program for Alliant Energy encourages economic development in IPL’s service territory.

Alliant Energy has various development-ready sites throughout Iowa, including the Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the Prairie View Industrial Center Super Park in Ames, Iowa.

In May 2024, legislation was enacted in Iowa related to the advance rate-making principles for certain generation and energy storage investments located in Iowa.

The most significant provisions of this legislation for Alliant Energy would allow IPL to include energy storage and nuclear-fired generation projects in the advance rate-making principles request process prior to making these investments in Iowa, and require IPL to obtain a certificate of public convenience, use and necessity (GCU Certificate) from the IUC in order to construct energy storage projects.

In July 2023, legislation was enacted in Wisconsin, which creates a sales and use tax exemption for the sale of certain property for qualified data centers.

The most significant provision of this legislation for Alliant Energy encourages economic development in WPL’s service territory.

In August 2022, the Inflation Reduction Act of 2022 was enacted.

The most significant provisions of the new legislation for Alliant Energy, IPL and WPL relate to a 10-year extension of tax credits for clean energy projects, a new production tax credit for eligible solar projects, a new stand-alone investment tax credit for battery storage projects and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers.

The most significant provisions of the legislation for Alliant Energy, IPL and WPL relate to a 10-year extension of tax credits for clean energy projects, a new production tax credit for eligible solar projects, a new stand-alone investment tax credit for energy storage projects and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers.

The new legislation also includes a requirement for corporations with income over $1 billion to pay a 15% minimum tax;

however, Alliant Energy is currently below this income level.

Alliant Energy, IPL and WPL are utilizing various provisions of the new legislation to enhance the tax benefits expected from their announced solar and battery storage projects, including transferring the future tax credits from such projects to other corporate taxpayers, as well as the repowering of existing wind farms.

The impact of these changes is expected to result in more cost benefits for IPL’s and WPL’s customers, higher rate base amounts, additional financing needs expected to be satisfied with additional long-term debt and common stock issuances, and improvements in long-term cash flows over the life of the solar, battery storage and wind repowering projects.

Refer to Note 1(c) for discussion of the transfer of renewable tax credits to other corporate taxpayers in 2023.

Refer to Note 12 for discussion of Iowa tax reform enacted in March 2022.

In November 2021, the Infrastructure Investment and Jobs Act (IIJA Act) was enacted.

The most significant provisions of the IIJA Act for Alliant Energy relate to a variety of infrastructure-related priorities, including transportation, environmental, energy and broadband infrastructure.

In addition, the IIJA Act is intended to accelerate research, development, demonstration and deployment of carbon-free technologies, including hydrogen and carbon capture and storage.

In March 2021, the American Rescue Plan Act of 2021 (Act) was enacted.

The most significant provision of the Act for Alliant Energy is reduced minimum pension plan funding requirements, which Alliant Energy adopted in August 2021.

The Act also provides additional funding to the Low Income Home Energy Assistance Program, which assists certain of Alliant Energy’s customers with managing their energy costs, as well as provides financial support for certain of Alliant Energy’s residential, small business and non-profit customers.

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Alliant Energy, IPL and WPL are utilizing various provisions of the new legislation to enhance the tax benefits expected from their current and planned renewable generation and energy storage projects, including transferring tax credits from such projects to other corporate taxpayers.

Repeal or amendment of the Inflation Reduction Act of 2022, or portions of the Inflation Reduction Act of 2022, could have an adverse impact on Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations.

Refer to Note 1(c) for discussion of the transfer of renewable tax credits to other corporate taxpayers in 2023 and 2024.

Refer to Note 1 1 for discussion of Iowa tax reform enacted in 2022.

LIQUIDITY AND CAPITAL RESOURCES

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Liquidity Position - At December 31, 2024, Alliant Energy had $81 million of cash and cash equivalents, $742 million ($275 million at the parent company, $250 million at IPL and $217 million at WPL) of available capacity under the single revolving credit facility and $40 million of available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Alliant Energy, IPL and WPL plan to maintain debt-to-total capitalization ratios that are consistent with investment-grade credit ratings.

IPL and WPL expect to maintain capital structures consistent with the authorized levels approved by regulators.

Capital Structure - Alliant Energy, IPL and WPL plan to maintain debt-to-total capitalization ratios that are consistent with investment-grade credit ratings, as well as maintain capital structures consistent with the authorized levels approved by IPL’s and WPL’s regulators.

Financial capital structures as of December 31, 2024 were as follows (Common Equity (CE);

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Short-term Debt (SD)):

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Alliant Energy, IPL and WPL intend to manage their capital structures and liquidity positions in such a way that facilitates their ability to raise funds reliably and on reasonable terms and conditions, while maintaining capital structures consistent with those approved by regulators.

In addition to capital structures, other important factors used to determine the characteristics of future financings include financial coverage ratios, capital spending plans, regulatory orders and rate-making considerations, levels of debt imputed by rating agencies, market conditions, the impact of tax initiatives and legislation, and any potential proceeds from asset sales.

In addition to capital structures, other important factors used to determine the characteristics of future financings include financial coverage ratios, capital spending plans, regulatory orders and rate-making considerations, levels of debt and equity imputed by rating agencies, market conditions, the impact of tax initiatives and legislation, and any potential proceeds from asset sales.

The PSCW factors certain imputed debt adjustments, including certain lease obligations, in establishing a regulatory capital structure as part of WPL’s retail rate reviews.

The IUB does not make any explicit adjustments for imputed debt in establishing capital ratios used in determining customer rates, although such adjustments are considered by IPL in recommending an appropriate capital structure.

The IUC does not make any explicit adjustments for imputed debt in establishing capital ratios used in determining customer rates, although such adjustments are considered by IPL in recommending an appropriate capital structure.

Debt imputations by rating agencies include, among others, pension and OPEB obligations, the sales of accounts receivable program and certain lease obligations.

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Cash, cash equivalents and restricted cash, December 31 $81 $63 $29 $53 $51 $7

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Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for 2024 compared to 2023 (in millions):

Alliant Energy IPL WPL

Higher collections from WPL’s retail electric and gas base rate increases $254 $87 $167

Changes in income taxes paid/received (a) 109 58 64

Changes in levels of production fuel 19 2 17

Timing of WPL’s fuel-related cost recoveries from retail electric customers (75) — (75)

Changes in gas stored underground 104 45 59

Changes in income taxes paid/refunded 94 81 6

Changes in the sales of accounts receivable at IPL (56) (56) —

Lower (higher) contributions to qualified defined benefit pension plans 38 50 (12)

Timing of intercompany payments and receipts — 28 35

Changes in interest payments (56) (19) (17)

Decreased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales (31) (17) (14)

Changes in cash collateral and deposit balances at Corporate Services (33) — —

Other (primarily due to other changes in working capital) 136 41 41

$300 $96 $183

Income Tax Payments and Refunds - Income tax (payments) refunds were as follows (in millions):

WPL (50) (56)

(a) Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers in 2023 and 2024.

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Income Tax Payments and Receipts - Income tax (payments) receipts were as follows (in millions):

IPL $175 $117

Other subsidiaries 8 21

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Alliant Energy, IPL and WPL currently do not expect to make any significant federal income tax payments over the next few years based on their current credit carryforward positions;

however, some tax payments and refunds may occur for state taxes and between consolidated group members (including IPL and WPL) under the tax sharing agreement between Alliant Energy and its subsidiaries.

however, some tax payments and receipts may occur for state taxes and between consolidated group members (including IPL and WPL) under the tax sharing agreement between Alliant Energy and its subsidiaries.

Refer to Note 1 1 for discussion of the carryforward positions.

As discussed in “ Legislative Matters ,” the Inflation Reduction Act of 2022 provides the right to transfer renewable tax credits to other corporate taxpayers.

Refer to the cash flows statements and Note 1 (c) for details of renewable tax credits transferred to other corporate taxpayers in 2023.

Refer to the cash flows statements and Note 1 (c) for details of renewable tax credits transferred to other corporate taxpayers in 2023 and 2024.

Alliant Energy, IPL and WPL currently intend to transfer all eligible renewable tax credits in the future, and as a result, expect an increase in future cash flows from operating activities.

Higher Earnings on Increasing Rate Base - Refer to “ Other Future Considerations ” for discussion of expected increases in future cash flows from operating activities resulting from higher earnings on increasing rate base at WPL.

Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $12 million, $— and $10 million of pension plan contributions in 2024, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2023 measurement date.

Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $20 million, $1 million and $14 million of pension plan contributions in 2025, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2024 measurement date.

Refer to Note 1 2 (a) for discussion of pension plan contributions in 2024 and the current funded levels of pension plans.

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Changes in the amount of cash receipts on sold receivables 140 140 —

Higher non-utility construction and acquisition expenditures (31) — —

Proceeds from sales of partial ownership interests in West Riverside in 2023 120 — 120

Other (b) (73) (56) (34)

Other 35 14 31

($146) ($358) $222

(a) Largely due to higher expenditures for IPL’s solar generation.

(b) Largely due to higher cash payments related to cost of removal obligations at IPL and WPL.

(a) Largely due to higher expenditures for IPL’s and WPL’s energy storage, IPL’s solar generation and IPL’s refurbishment of an existing wind farm, partially offset by lower expenditures for WPL’s solar generation.

Construction and Acquisition Expenditures - Construction and acquisition expenditures and financing plans are reviewed, approved and updated as part of the strategic planning process.

Changes may result from a number of reasons, including regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems.

Changes may result from a number of reasons, including changes in expected load growth, regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems.

Refer to “ Rate Matters ” for discussion of an electric distribution system investment cap included in IPL’s rate review settlement agreement, which was approved by the IUC in September 2024.

Alliant Energy, IPL and WPL have not yet entered into contractual commitments relating to the majority of their anticipated future construction and acquisition expenditures.

As a result, they

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have some discretion with regard to the level and timing of these expenditures.

The table below summarizes anticipated construction and acquisition expenditures (in millions), which are focused on the transition to cleaner energy and strengthening the resiliency and reliability of IPL’s and WPL’s electric grid, and include renewables and battery storage projects, dispatchable gas generation projects and wind repowering projects.

As a result, they have some discretion with regard to the level and timing of these expenditures.

The table below summarizes anticipated construction and acquisition expenditures (in millions), which are focused on adding generation to meet growing customer demand for electricity, including initial expected future data center growth, and strengthening the resiliency and reliability of the electric grid, and include renewable generation and energy storage projects, dispatchable gas generation projects and converting certain coal-fired EGUs to natural gas.

Alliant Energy, IPL and WPL are currently evaluating the impact of additional potential large load growth customers on their resource plans and will update their anticipated construction and acquisition expenditures as needed in the future.

Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of construction expenditures and exclude AFUDC and capitalized interest, if applicable.

Refer to “ Customer Investments ” for further discussion of certain key projects impacting construction and acquisition plans related to the utility business.

Refer to “ Customer Investments ” for further discussion of certain key utility business projects impacting construction and acquisition plans, and the related regulatory filings.

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Alliant Energy IPL WPL

2025 2026 2027 2028 2025 2026 2027 2028 2025 2026 2027 2028

Renewables and battery storage projects $1,140 $665 $780 $775 $575 $275 $445 $205 $565 $390 $335 $570

Renewables and energy storage projects $800 $1,115 $1,325 $1,340 $455 $540 $595 $565 $345 $575 $730 $775

Gas projects 390 570 780 655 145 175 365 355 195 365 415 300

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$2,205 $2,680 $3,020 $2,960 $1,055 $1,135 $1,365 $1,300 $955 $1,370 $1,530 $1,490

Renewables and Battery Storage - Refer to “ Customer Investments ” for further discussion of regulatory filings with the IUB and PSCW related to future renewable and battery storage projects.

West Riverside Options - WPL entered into agreements with neighboring utilities that provide them options to purchase a partial ownership interest in West Riverside.

Upon exercise of such options and the resulting sales, WPL receives proceeds from the sales.

Refer to “ Customer Investments ” for additional information, including partial sales in 2023 and potential additional partial sales in the future.

West Riverside Options - WPL entered into agreements with neighboring utilities that provided them options to purchase a partial ownership interest in West Riverside.

Upon exercise of such options and the resulting sales, WPL received proceeds from the sales in 2023 and 2024.

Refer to “ Customer Investments ” for additional information.

Renewable Tax Credits - IPL and WPL started construction in 2024, and currently expect to start construction in the first half of 2025, of certain renewable and energy storage projects, with the intention of preserving the qualification of any renewable tax credits associated with these projects.

Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for 2024 compared to 2023 (in millions):

Alliant Energy IPL WPL

Higher net proceeds from common stock issuances $221 $— $—

Lower payments to retire long-term debt 125 — 250

Higher (lower) net proceeds from issuance of long-term debt 117 296 (291)

Net changes in the amount of commercial paper outstanding (294) — (26)

Higher payments to retire long-term debt ($301) ($500) $—

Lower net proceeds from common stock issuances (223) — —

(Higher) lower common stock dividends (36) 80 (12)

Net changes in the amount of commercial paper outstanding 250 50 (163)

Higher net proceeds from issuance of long-term debt 158 347 —

Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy — 245 (190)

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In 2023, IPL received authorization from FERC to issue securities in 2024 and 2025 as follows (in millions):

Initial Authorization Remaining Capacity as of December 31, 2024

Long-term debt securities issuances in aggregate $1,700 $1,050

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IPL’s and WPL’s shelf registration statements may be used to issue preferred stock and debt securities.

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Common Stock Dividends - Payment of common stock dividends is subject to dividend declaration by Alliant Energy’s Board of Directors and is dependent upon, among other factors, regulatory limitations, earnings, cash flows, capital requirements and general financial condition of subsidiaries.

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Refer to “ Results of Operations ” for discussion of expected common stock dividends in 2025.

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Common Stock Issuances - Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2023 and 2024, and “ Results of Operations ” for discussion of expected issuances of common stock in 2025.

Short-term Debt - In January 2024, Alliant Energy, IPL and WPL extended their single revolving credit facility agreement, which expires in December 2028 and is discussed in Note 9(a) .

Short-term Debt - In December 2024, Alliant Energy, IPL and WPL amended and extended their single revolving credit facility agreement, which expires in December 2029 and is discussed in Note 8 (a) .

There are currently 14 lenders that participate in the credit facility, with respective commitments ranging from $25 million to $130 million.

Subject to certain conditions, Alliant Energy, IPL and WPL may exercise one extension option, which would extend the maturity date by one year.

Subject to certain conditions, Alliant Energy, IPL and WPL may exercise two extension options, which would each extend the maturity date by one year.

The credit facility has a provision to expand the facility size up to an additional $700 million, for a potential total commitment of $2 billion, subject to lender approval for Alliant Energy and subject to lender and regulatory approvals for IPL and WPL.

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Long-term Debt - Refer to Note 8 (b) for discussion of issuances and retirements of long-term debt in 2024, and “ Results of Operations ” for discussion of expected issuances and retirements of long-term debt in 2025.

In 2022, WPL issued $600 million of 3.95% green bond debentures due 2032, and an amount in excess of the net proceeds was disbursed for the development and acquisition of WPL’s solar EGUs.

In 2022, AEF entered into a $300 million variable rate term loan credit agreement and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in 2022.

In 2022, AEF increased the amount outstanding under the new term loan credit agreement by $100 million and used the additional borrowings to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes.

In 2023, IPL issued $300 million of 5.7% senior debentures due 2033, and used the net proceeds to reduce cash amounts received from its sales of accounts receivable program, reduce commercial paper classified as long-term debt, and for general corporate purposes;

pending application of the proceeds, such proceeds were placed in money market fund investments.

In 2023, WPL issued $300 million of 4.95% green bond debentures due 2033, and an amount equal to or in excess of the net proceeds was disbursed for the development and acquisition of its solar EGUs.

In 2023, AEF issued $300 million of 5.95% senior notes due 2029 and used the net proceeds to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes.

In 2023, AEF entered into a $300 million interest rate swap maturing in January 2026 to mitigate interest rate risk.

Under the terms of the swap, AEF exchanged a variable interest rate for a fixed interest rate of 3.93% on a portion of its variable-rate term loan borrowings.

In 2023, Alliant Energy issued $575 million of 3.875% convertible senior notes due 2026, and used the net proceeds for general corporate purposes.

Impact of Credit Ratings on Liquidity and Collateral Obligations -

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Senior unsecured long-term debt BBB+ N/A

Outlook Stable Stable

Outlook Negative Stable

Corporate/issuer A- Baa1

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Senior unsecured long-term debt A- Baa1

Outlook Stable Stable

Outlook Negative Stable

Corporate/issuer A Baa1

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Each of Alliant Energy, IPL or WPL assumes no obligation to update their respective credit ratings.

Refer to Note 15 for additional information on ratings triggers for commodity contracts accounted for as derivatives.

Refer to N ote 1 4 for additional information on ratings triggers for commodity contracts accounted for as derivatives.

Off-Balance Sheet Arrangements -

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The purchase commitment from the third party to which IPL sells its receivables expires in March 2026.

IPL currently expects to amend and extend the purchase commitment.

In 2024 and 2023, IPL evaluated the third party that purchases IPL’s receivable assets under the Receivables Agreement and believes that the third party is a VIE;

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IPL’s electric and gas tariffs and WPL’s wholesale electric and gas tariffs provide for subsequent monthly adjustments to their tariff rates for material changes in prudently incurred commodity costs.

IPL’s and WPL’s rate mechanisms, combined with commodity derivatives, significantly reduce commodity risk associated with their electric and gas

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IPL’s and WPL’s rate mechanisms, combined with commodity derivatives, significantly reduce commodity risk associated with their electric and gas service.

WPL’s retail electric service is exposed to the impact of changes in commodity prices due largely to the current retail recovery mechanism in place in Wisconsin for fuel-related costs.

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Counterparty Credit Risk - Alliant Energy, IPL, and WPL are exposed to credit risk related to losses resulting from counterparties’ nonperformance of their contractual obligations.

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In addition, Alliant Energy and IPL are exposed to risk resulting from changes in interest rates on cash amounts outstanding under IPL’s sales of accounts receivable program.

Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2023, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $5 million, $0 and $3 million, respectively.

Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2024, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $6 million, $1 million and $2 million, respectively.

Refer to Notes 5(b) and 8 for additional information on cash amounts outstanding under IPL’s sales of accounts receivable program, and short- and long-term variable-rate borrowings, respectively.

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Assumptions and judgments are made each reporting period regarding whether regulatory assets are probable of future recovery and regulatory liabilities are probable future obligations by considering factors such as regulatory environment changes, rate orders issued by the applicable regulatory agencies, historical decisions by such regulatory agencies regarding similar regulatory assets and regulatory liabilities, and subsequent events of such regulatory agencies.

The decisions made by regulatory authorities have an impact on the recovery of costs, the rate of return on invested capital and the timing and amount of assets to be recovered by rates.

The decisions made by regulatory agencies have an impact on the recovery of costs, the rate of return on invested capital and the timing and amount of assets to be recovered by rates.

A change in these decisions may result in a material impact on results of operations and the amount of assets and liabilities in the financial statements.

In May 2023, IPL retired the Lansing Generating Station.

IPL is currently allowed a full recovery of and a full return on this EGU from both its retail and wholesale customers, and IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period includes a request for continued recovery of and a return on the remaining net book value of Lansing through 2037.

As a result, Alliant Energy and IPL concluded that no impairment was required as of December 31, 2023.

IPL was previously allowed a full recovery of and a full return on this EGU from its retail customers.

In September 2024, the IUC approved IPL’s retail electric rate review for the October 2024 through September 2025 forward-looking Test Period, which includes a return of the remaining net book value of Lansing;

however, the IUC did not approve a return on the remaining net book value of Lansing, therefore the return on the remaining net book value is no longer recoverable from IPL’s retail electric customers.

As a result a pre-tax non-cash charge of $60 million was recorded to “Asset valuation charge for IPL’s Lansing Generating Station” in Alliant Energy’s and IPL’s income statements in 2024, with a corresponding decrease in Alliant Energy’s and IPL’s assets retired early regulatory assets.

IPL is currently allowed a full recovery of and a full return on this EGU from its wholesale customers.

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Significant changes in these judgments and assumptions could have a material impact on financial condition and results of operations.

Alliant Energy’s and IPL’s critical assumptions and judgments for 2023 included estimates of qualifying deductions for repairs expenditures and allocation of mixed service costs due to the impact of Iowa rate-making principles on such property-related differences.

Alliant Energy’s and IPL’s critical assumptions and judgments for 2024 included estimates of qualifying deductions for repairs expenditures, allocation of mixed service costs and state depreciation, and costs related to retirement or removal of depreciable property due to the impact of Iowa rate-making principles on such property-related differences.

Critical assumptions and judgments also include projections of future taxable income used to determine the ability to utilize federal credit carryforwards prior to their expiration.

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Effect of Rate-making on Property-related Differences - Alliant Energy’s and IPL’s effective income tax rates are normally impacted by certain property-related differences at IPL for which deferred tax is not recorded in the income statement pursuant to Iowa rate-making principles.

Changes in methods or assumptions regarding the amount of IPL’s qualifying repairs expenditures, allocation of mixed service costs, and costs related to retirement or removal of depreciable property could result in a material impact on Alliant Energy’s and IPL’s financial condition and results of operations.

Changes in methods or assumptions regarding the amount of IPL’s qualifying repairs expenditures, allocation of mixed service costs and state depreciation, and costs related to retirement or removal of depreciable property, could result in a material impact on Alliant Energy’s and IPL’s financial condition and results of operations.

Carryforward Utilization - Significant federal tax credit carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2024.

Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards more than five years before expiration.

Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards approximately five years before expiration.

Changes in tax regulations or assumptions regarding current and future taxable income could require valuation allowances in the future resulting in a material impact on financial condition and results of operations.

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The long-lived assets assessed for impairment generally include certain assets within regulated operations that may not be fully recovered from IPL’s and WPL’s customers as a result of regulatory decisions in the future, and assets within non-utility operations that are proposed to be sold or are currently generating operating losses.

Regulated Operations - Alliant Energy’s, IPL’s and WPL’s long-lived assets within their regulated operations that were assessed for impairment and/or plant abandonment in 2023 included WPL’s generating units subject to early retirement, and IPL’s and WPL’s solar generation projects recently completed or under construction.

Generating Units Subject to Early Retirement - Alliant Energy, IPL and WPL evaluate future plans for their electric generation fleet and have announced the early retirement of certain EGUs.

When it becomes probable that an EGU will be retired before the end of its useful life, Alliant Energy, IPL and WPL must assess whether the EGU meets the criteria to be considered probable of abandonment.

Regulated Operations - Alliant Energy’s, IPL’s and WPL’s long-lived assets within their regulated operations that were assessed for impairment and/or plant abandonment in 2024 included WPL’s generating units subject to early retirement and solar generation projects.

Generating Units Subject to Early Retirement - Alliant Energy and WPL evaluate future plans for their electric generation fleet and have announced the early retirement of certain EGUs.

When it becomes probable that an EGU will be retired before the end of its useful life, Alliant Energy and WPL must assess whether the EGU meets the criteria to be considered probable of abandonment.

EGUs that are considered probable of abandonment generally have material remaining net book values and are expected to cease operations in the near term significantly before the end of their original estimated useful lives.

If an EGU meets such criteria to be considered probable of abandonment, Alliant Energy, IPL and WPL must assess the probability of full recovery of the remaining carrying value of such EGU.

If an EGU meets such criteria to be considered probable of abandonment, Alliant Energy and WPL must assess the probability of full recovery of the remaining carrying value of such EGU.

If it is probable that regulators will not allow full recovery of and a full return on the remaining net book value of the abandoned EGU, an impairment charge is recognized equal to the difference between the remaining carrying value and the present value of the future revenues expected from the abandoned EGU.

Alliant Energy and WPL concluded that Edgewater Unit 5 (expected to be retired by June 1, 2025) and Columbia Units 1 and 2 (expected to be retired by June 1, 2026), met the criteria to be considered probable of abandonment as of December 31, 2023.

WPL is currently allowed a full recovery of and a full return on these EGUs from both its retail and wholesale customers, and as a result, Alliant Energy and WPL concluded that no impairment was required as of December 31, 2023.

Alliant Energy and WPL concluded that the coal-fired Columbia Units 1 and 2 met the criteria to be considered probable of abandonment as of December 31, 2024.

WPL currently plans to cease coal operations at Columbia Units 1 and 2 by the end of 2029, as well as evaluate the conversion of Columbia Unit 1 and/or Unit 2 to natural gas.

WPL is currently allowed a full recovery of and a full return on the Columbia EGUs from both its retail and wholesale customers, and as a result, Alliant Energy and WPL concluded that no impairment was required as of December 31, 2024.

Alliant Energy, IPL and WPL evaluated their other EGUs that are subject to early retirement and determined that no other EGUs met the criteria to be considered probable of abandonment as of December 31, 2024.

Note 3 provides additional details on these EGUs.

Solar Generation Projects Recently Completed or Under Construction - Alliant Energy, IPL and WPL review property, plant and equipment for possible impairment whenever events or changes in circumstances indicate all or a portion of the carrying value of the assets may be disallowed for rate-making purposes.

If IPL or WPL is disallowed recovery of any portion of, or is only allowed a partial return on, the carrying value of the solar generation projects recently completed or under construction, then an impairment charge is recognized.

“ Customer Investments ” provides details of IPL’s and WPL’s solar generation projects recently completed or under construction.

IPL accepted the IUB’s advance rate-making principles approved in October 2023 for 400 MW of solar generation.

IPL currently expects estimated construction costs associated with the 400 MW of new solar generation will exceed the cost target of $1,650/kilowatt, including AFUDC and transmission upgrade costs among other costs, approved by the IUB by approximately 10%.

Alliant Energy and IPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of December 31, 2023 given construction costs were reasonably and prudently incurred.

WPL previously received authorization from the PSCW to acquire, construct, own and/or operate approximately 1,100 MW of new solar generation.

Alliant Energy and WPL currently expect estimated construction costs associated with this solar

Solar Generation Projects - Alliant Energy and WPL review property, plant and equipment for possible impairment whenever events or changes in circumstances indicate all or a portion of the carrying value of the assets may be disallowed for rate-making purposes.

If WPL is disallowed recovery of any portion of, or is only allowed a partial return on, the carrying value of its solar generation projects, then an impairment charge is recognized.

Alliant Energy and WPL currently expect construction costs associated with WPL’s approximately 1,100 MW of new solar generation will exceed the construction cost estimates previously approved by the PSCW by approximately $205 million.

In 2024, the PSCW issued orders approving deferral of, and the deferral of a return on, the incremental solar generation construction costs in 2024 and 2025.

Alliant Energy and WPL concluded that there was not a probable disallowance of higher rate base amounts as of December 31, 2024 given construction costs were reasonably and prudently incurred.

“ Customer Investments ” provides details of WPL’s solar generation projects recently completed.

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generation will exceed amounts previously approved by the PSCW by approximately $180 million.

In December 2023, the PSCW issued an order authorizing annual base rate increases for WPL’s retail electric customers for the 2024/2025 forward-looking Test Period, which did not include revenue requirement for the estimated construction costs that exceed amounts previously approved by the PSCW.

In February 2024, the PSCW issued an oral decision approving WPL’s deferral request to seek recovery of these costs in a future regulatory proceeding.

Alliant Energy and WPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of December 31, 2023 given construction costs were reasonably and prudently incurred.

AROs - The fair value of a legal obligation associated with the retirement of an asset is recorded as a liability when an asset is placed in service, when a legal obligation is subsequently identified or when sufficient information becomes available to determine a reasonable estimate of the fair value of future retirement costs.

Alliant Energy, IPL and WPL estimate the fair value of their AROs using present value techniques, in which they make various assumptions, including estimates of the amounts and timing of future cash flows associated with retirement activities, inflation and discount rates.

Estimates of the timing and amounts of future cash outlays are based on projections of when and how assets will be retired and the cost of future removal activities.

The estimates are subject to change and future updates could have a material impact on Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations.

In 2024, substantially due to the enactment of the revised CCR Rule, which significantly expands the scope of regulation to include coal ash ponds at sites that no longer produce electricity and inactive landfills, Alliant Energy, IPL and WPL recorded additional AROs of $409 million, $201 million and $208 million, respectively.

These amounts are expected to be adjusted in the future, as additional information is obtained for the specific site closure plans, including the determination of whether or not individual sites are considered legal obligations and the acceptance and approval of compliance approaches, which could change management assumptions and result in a material change to the recorded ARO amounts.

Refer to Note 1 3 for further discussion of AROs.

Pensions and Other Postretirement Benefits - Alliant Energy, IPL and WPL sponsor various defined benefit pension and OPEB plans that provide benefits to a significant portion of their employees and retirees.

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The estimates made in accounting for contingencies, and the gains and losses that are recorded upon the ultimate resolution of these uncertainties, could have a significant effect on results of operations and the amount of assets and liabilities in the financial statements.

Certain contingencies, such as Alliant Energy Resources, LLC’s guarantees of the partnership obligations of an affiliate of Whiting Petroleum, require estimation each reporting period of the expected credit losses on those contingencies, which requires significant judgment and may result in the recognition of a credit loss liability.

With respect to Alliant Energy’s guarantees of the partnership obligations of an affiliate of Whiting Petroleum, the most significant judgments in determining the credit loss liability were the estimate of the exposure under the guarantees and the methodology used for calculating the credit loss liability.

As of December 31, 2023, Alliant Energy currently estimates the exposure to be a portion of the known partnership abandonment obligations.

The methodology used to determine the credit loss liability considers both quantitative and qualitative information, which utilizes potential outcomes in a range of possible estimated amounts.

Factors considered include market and external data points, the creditworthiness of the other partners, Whiting Petroleum’s emergence from bankruptcy in 2020 as well as subsequent bankruptcy developments, payments by Whiting Petroleum related to abandonment obligations, forecasted cash flow expenditures associated with the abandonment obligations based on information made available to Alliant Energy, and Whiting Petroleum’s business combination with Oasis Petroleum Inc.

Certain contingencies require estimation each reporting period of the expected credit losses on those contingencies, which requires significant judgment and may result in the recognition of a credit loss liability.

Note 1 6 provides further discussion of contingencies assessed at December 31, 2024 that may have a material impact on financial condition and results of operations, including various pending legal proceedings, guarantees and indemnifications.

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Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 7. Management’s Discussion and Analysis