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Item 7. Management’s Discussion and Analysis

2026-02-20 compared with 2025-02-21 · 243 added, 239 removed, 428 unchanged (53% of the section changed)

MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

This MDA includes information relating to Alliant Energy, IPL and WPL, as well as AEF and Corporate Services.

This MDA includes information relating to Alliant Energy, IPL and WPL (collectively, the Utilities), as well as ATC Holdings, AEF and Corporate Services.

Where appropriate, information relating to a specific entity has been segregated and labeled as such.

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Mission, Purpose and Strategy

Alliant Energy’s mission is to deliver affordable energy solutions and exceptional service that its customers and the communities it serves count on - affordably, safely, reliably, and sustainably.

This mission aligns with Alliant Energy’s purpose - to serve customers and build stronger communities - which guides it through the ever-changing dynamics of the economy and the energy industry.

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 evolving customer expectations, providing an attractive return for investors, and advancing emerging technologies with safe, secure energy production.

Alliant Energy’s mission is to deliver the energy solutions and exceptional service that its customers and communities count on - affordably, safely, reliably and responsibly.

This mission aligns with Alliant Energy’s purpose - to serve customers and build stronger communities - which guides it through the evolving dynamics of the economy and the energy industry.

Alliant Energy leads as a corporate citizen, advancing environmental stewardship and supporting the communities in its service territories.

Alliant Energy’s mission and purpose are supported by a strategy focused on meeting evolving customer expectations, delivering attractive returns for investors, and advancing emerging technologies and generation to enable safe, secure and future-ready 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.

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

Key Highlights -

• 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.

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.

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, energy storage and wind refurbishment projects.

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.

• Alliant Energy’s resource plan is the roadmap for building a strong and resilient energy future to meet the growing energy needs across Iowa and Wisconsin.

This long-term plan expands generation capacity and includes a balanced mix of natural gas, energy storage, new renewable generation, improvements at existing natural gas-fired EGUs and refurbishments at existing wind farms.

It is designed to deliver the reliable, affordable energy customers count on by efficiently increasing the capabilities of existing generation through gas and wind facility upgrades while also building larger scale natural gas facilities to capture economies of scale.

Alliant Energy’s industry-leading wind and solar energy resources provide zero-fuel cost generation as well as generate renewable tax credits that are provided to its electric customers.

By enhancing new and existing energy sources while maximizing traditional energy sources, Alliant Energy is helping support economic growth, maintain reliability and keep customer bills affordable.

At the same time, Alliant Energy is modernizing its distribution system to create a smarter, more adaptable infrastructure that increases resiliency and supports evolving energy technologies.

By advancing a responsible approach to energy resources, Alliant Energy can deliver what matters most to the customers and communities it serves - affordably, safely and reliably.

• Higher electric capacity revenues from existing generation resources beginning in 2025 are expected to provide cost benefits to WPL’s retail electric customers in the future through its fuel cost recovery mechanism.

• 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 provided to customers that are 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 $285 million, $216 million and $98 million of proceeds from renewable tax credits transferred to other corporate taxpayers in 2025, 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’s retail electric and gas customers began receiving these benefits with the new base rates effective October 1, 2024.

• IPL provided billing credits to its retail electric customers through the tax benefit rider of $52 million and $16 million in 2025 and 2024, respectively.

IPL also provided its retail electric customers $162 million and $40 million in credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism in 2025 and 2024, respectively.

• 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.

Refer to Note 12 for discussion of this program.

• 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.

Department of Energy Office of Energy Dominance Financing, formerly the 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 eligible projects as defined in the governing agreement.

• 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 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.

Department of Energy Office of Electricity - formerly administered by the 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 April 2025, WPL submitted an application to the U.S.

Army Corps of Engineers for up to $45 million in loans through the Corps Water Infrastructure Financing Program.

If finalized, such loans would provide low interest financing for various proposed safety projects at WPL’s Kilbourn and Prairie du Sac hydro EGUs.

• IPL and WPL executed agreements to enable fiber connectivity to one of its data center customers by leasing underground conduit in their service territories, which is expected to provide cost benefits to IPL’s and WPL’s existing customers.

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

Alliant Energy’s capital allocation strategy is focused on:

Developing energy resources to meet demand for future phases of economic development and transmission investments through ATC.

• Reliability and Resiliency:

Investments to extend the flexibility, efficiency, capacity and optionality of existing resources including coal plant conversions and replacements, resiliency investments in natural gas storage, liquified natural gas and gas delivery, as well as reliability and safety investments in electric and gas distribution.

• Customer Value:

Improving customer and employee experiences through technology investments that increase operational efficiency, service effectiveness and organizational agility.

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

• 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.

• 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 1,600 MW of new natural gas resources, approximately 1,000 MW of new energy storage, approximately 1,300 MW of new renewable generation, improvements of approximately 410 MW at existing natural gas-fired EGUs, and refurbishments at approximately 450 MW of existing wind farms.

Alliant Energy is currently evaluating the impact of potential additional demand from 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.

• Completion of construction of energy storage projects totaling 175 MW at WPL and 99MW at IPL in 2025.

• Completion of the Neenah Unit 1 and Sheboygan Falls Unit 1 advanced gas path projects in 2025, which increased the efficiency and capacity at each of these facilities.

• 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.

Growing customer demand - Alliant Energy’s strategy supports expanding electric and gas usage in its service territories by promoting electrification initiatives and economic development to grow at the pace of its customers.

Key Highlights -

• IPL has entered into electric service agreements with two new customers, and WPL has entered into an electric service agreement with one new customer, each of whom is constructing or expects to construct one or more data centers in IPL’s or WPL’s service territories.

IPL’s and WPL’s currently executed electric service agreements include aggregate, peak demands of approximately 3 gigawatts.

The energy resources to serve this expected load are included in the construction and acquisition table in “ Liquidity and Capital Resources .” The actual timing and amount of increases in IPL’s and WPL’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.

• 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.

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

• In May 2025 and October 2025, the IUC issued orders, with certain conditions, approving individual customer rates for data centers expected to be constructed in IPL’s service territory.

In April 2025, WPL filed a request with the PSCW for approval of an individual customer rate for a data center expected to be constructed in its service territory.

A decision from the PSCW is currently expected in the second quarter of 2026.

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

RESULTS OF OPERATIONS

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Alliant Energy Consolidated $810 $3.14 $690 $2.69

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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Alliant Energy’s Utilities and Corporate Services net income increased by $153 million in 2025 compared to 2024.

The increase was primarily due to higher revenue requirements from capital investments, estimated temperature impacts on retail electric and gas sales, an asset valuation charge for IPL’s Lansing Generating Station as a result of the IUC order for IPL’s retail electric rate review in 2024, restructuring and voluntary separation charges in 2024, and an ARO charge allocated to the steam business at IPL due to the revised CCR Rule in 2024.

These items were partially offset by higher other operation and maintenance expenses, depreciation and financing expenses.

Alliant Energy’s Non-utility and Parent net income decreased by $34 million in 2025 compared to 2024, primarily due to an asset valuation charge for Alliant Energy’s non-utility business in 2025, higher financing expense and a state income tax apportionment charge in 2025, partially offset by an adjustment of deferred tax assets due to Iowa tax reform in 2024.

Net Income Variances - The following items contributed to increased (decreased) net income for 2025 compared to 2024 (in millions):

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Changes in gas utility (Refer to details below )

(75) (50) (25)

Changes in other utility (3) (2) (1)

Changes in non-utility (1) — —

Changes in total revenues 381 162 220

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Changes in electric production fuel and purchased power (Refer to details below )

(114) (14) (100)

Changes in electric transmission service (Refer to details below )

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

(39) (7) (32)

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 (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)

(64) (15) (27)

Changes in depreciation and amortization (Higher primarily due to solar generation placed in service in 2024 and updated electric depreciation rates for IPL effective October 1, 2024) (74) (59) (13)

Changes in taxes other than income taxes 1 1 1

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Changes in interest expense (Higher primarily due to financings completed in 2024 and 2025) (63) (34) (8)

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

Changes in AFUDC 14 13 1

Changes in Other (4) (5) (4)

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Changes in net income $120 $95 $56

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Electric and Gas Revenues and Sales Summary - Electric and gas revenues (in millions), and MWh and Dth sales (in thousands), were as follows:

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$1,801 $1,625 16,958 17,489 $260 $215 104,305 102,160

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):

Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes increased 2% in 2025 compared to 2024, primarily due to changes in temperatures and higher sales to commercial and industrial customers.

Alliant Energy’s retail gas sales volumes increased 14% in 2025 compared to 2024, primarily due to changes in temperatures.

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

2025 2024 Change 2025 2024 Change

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Gas Transportation/Other - Gas transportation/other sales volume changes were largely due to changes in the gas volumes supplied to Alliant Energy’s natural gas-fired EGUs caused by the availability and dispatch of such EGUs.

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Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for 2025 compared to 2024 (in millions):

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Higher revenue requirements (a)(b) $333 $271 $62

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)

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 sales for resale bulk power and other revenues (c) 78 34 44

Estimated changes in sales volumes caused by temperatures 45 27 18

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 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 1(g) )

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) )

Changes in WPL electric fuel-related costs, net of recoveries (d) 8 — 8

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

Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (offset by changes in income taxes) (a) (122) (122) —

Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider (partially offset by changes in income taxes) (a) (36) (36) —

Lower revenues at IPL from discontinuation of renewable energy rider in 2024 (a) (24) (24) —

Lower wholesale revenues at IPL primarily due to lower sales from the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025 (22) (22) —

Other (1) 13 (14)

$325 $149 $176

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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) In December 2023, the PSCW issued an order authorizing an annual base rate increase of $60 million for WPL’s retail electric customers, covering the 2025 forward-looking Test Period, which reflects revenue requirement impacts of increasing electric rate base including investments in solar generation and energy storage.

(c) Sales for resale bulk power and other revenues increased primarily due to higher prices for electricity and capacity sold by IPL and WPL to MISO wholesale energy markets.

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

(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.

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Alliant Energy IPL WPL

Lower revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below)

($75) ($42) ($33)

Higher revenues due to changes in gas costs (Refer to Cost of Gas Sold Expense Variances below)

Estimated changes in sales volumes caused by temperatures 17 8 9

Higher revenue requirements (a) 6 6 —

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

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

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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 2025 compared to 2024 (in millions):

Alliant Energy IPL WPL

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

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 )

Higher electric production fuel costs (a) ($63) ($41) ($22)

Changes in WPL refunds/collections of previous over-/under-collection of retail electric fuel-related costs (offset in electric utility revenue) (Refer to Note 1(g) )

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.

(Higher) lower purchased power expense (b) (5) 20 (25)

($114) ($14) ($100)

(a) Electric production fuel costs increased primarily due to higher coal volumes due to higher dispatch of coal-fired EGUs and higher natural gas prices, partially offset by lower natural gas volumes due to lower dispatch of natural gas-fired EGUs.

(b) Purchased power expense increased primarily due to higher prices for electricity purchased by WPL, partially offset by lower volumes of electricity purchased at IPL.

Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for 2025 compared to 2024 (in millions):

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Changes in regulatory recovery for the difference between actual electric transmission service costs and those costs used to determine rates (Refer to Note 1(g) )

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

Other (primarily due to changes in transmission service costs provided by third parties) (27) (9) (18)

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Alliant Energy IPL WPL

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

Changes in retail gas volumes and natural gas prices ($43) ($12) ($31)

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

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Alliant Energy IPL WPL

Higher generation and energy delivery expenses ($26) ($8) ($18)

Higher incentive compensation expense (20) (11) (9)

Asset valuation charge for Alliant Energy’s non-utility business in 2025 (Refer to Note 17)

Development costs for new generation (14) (6) (8)

Higher energy efficiency expense at IPL (mostly offset by higher revenues) (11) (11) —

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 (24) (12) (4)

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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.

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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• Financing Plans - Alliant Energy currently expects to issue up to $2.4 billion of common stock in aggregate from 2026 through 2029 through the distribution agreement that was executed in May 2025, its Shareholder Direct Plan (up to $25 million in common stock annually) and additional future equity offerings.

Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2025 and Alliant Energy’s at-the-market offering program.

In 2026, IPL and WPL currently expect to issue up to $500 million and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $400 million of long-term debt in aggregate.

AEF and Alliant Energy at the parent company level have $500 million ($300 million term loan was retired in January 2026) and $575 million, respectively, of long-term debt maturing in 2026.

• Common Stock Dividends - Alliant Energy announced a 5% increase in its targeted 2026 annual common stock dividend to $2.14 per share, which is equivalent to a quarterly rate of $0.535 per share, beginning with the February 2026 dividend payment.

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, 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.

• Higher Earnings on Increasing Rate Base - Alliant Energy and WPL currently expect increases in electric utility and gas utility revenues in 2026 compared to 2025 due to impacts from increasing revenue requirements related to investments in the utility business (refer to “ Rate Matters ” for further discussion).

Additionally, Alliant Energy and IPL currently expect electric utility revenues to increase in 2026 compared to 2025 due to the expiration of tax benefit rider credits in 2025.

Furthermore, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2026 compared to 2025 due to additional renewable tax credits from renewable generation and energy storage projects placed in service in 2025 and/or expected to be placed in service in 2026.

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.

Investment tax credits resulting from IPL energy storage projects placed in service in 2025 and/or expected to be placed in service in 2026 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.

• Sales Trends - Alliant Energy, IPL and WPL currently expect an increase in retail electric sales in 2026 compared to 2025 driven by expected load growth from new customers who currently expect to build data centers in IPL’s and WPL’s service territories.

Refer to “ Growing Customer Demand ” for further discussion.

• Other Operation and Maintenance Expenses - Alliant Energy, IPL and WPL currently expect an increase in other operation and maintenance expenses in 2026 compared to 2025 largely due to 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 2026 compared to 2025 due to capital projects placed in service in 2025 and 2026.

• Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2026 compared to 2025 due to financings completed in 2025 and planned in 2026 as discussed above.

• Allowance for Funds Used During Construction - Alliant Energy, IPL and WPL currently expect an increase in AFUDC in 2026 compared to 2025 largely due to changes in CWIP balances related to construction activity on capital projects.

CUSTOMER INVESTMENTS

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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.

Alliant Energy’s current resource plan guides the addition of resources in Iowa and Wisconsin to meet customer demand for energy solutions that are affordable, safe, reliable, and responsibly delivered.

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 1,600 MW of new natural gas resources, approximately 1,000 MW of new energy storage, approximately 1,300 MW of new renewable generation, improvements of approximately 410 MW at existing natural gas-fired EGUs, and refurbishments at approximately 450 MW of existing wind farms.

Estimated capital expenditures for these planned projects for 2026 through 2029 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.

New Solar - In 2022 through 2024, WPL completed 1,089 MW of new solar generation projects in Wisconsin.

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.

New 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 were placed in service in July and October 2025, respectively, 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.

Department of Energy Office of Electricity - formerly administered by the 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 June 2025, WPL received an order from the PSCW authorizing the construction of the energy storage system.

Any grant proceeds are expected to reduce the cost of the project for WPL’s customers.

In February 2025, WPL filed a CA application with the PSCW for approval to construct a 2 billion cubic feet, or 25 million gallon, liquified natural gas facility in Rock County, Wisconsin.

A decision from the PSCW is currently expected in the second quarter of 2026.

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.

New Wind - In April 2025, WPL filed a CA application with the PSCW for approval to construct, own and operate the Bent Tree North EGU, an approximately 153 MW wind farm.

A decision from the PSCW is currently expected in the second quarter of 2026.

In January 2026, WPL filed a CA application with the PSCW for approval to acquire, construct, own and place into service an approximately 277 MW wind farm in Columbia County, Wisconsin.

The CA application also included a request for approval of an agreement between WPL and an affiliated subsidiary of AEF, under which WPL would acquire wind development assets from the affiliate.

A decision from the PSCW is currently expected in the first quarter of 2027.

New Natural Gas-fired Electric Generation - In April 2025, the PSCW issued an order authorizing WPL to construct, own and operate a 17.5 MW natural gas-fired EGU using Reciprocating Internal Combustion Engine (RICE) technology, at the site of its Riverside Energy Center.

In 2025, the Neenah Unit 1 and Sheboygan Falls Unit 1 advanced gas path projects were completed, which increased the efficiency and capacity at each of these EGUs.

The Neenah Unit 2 and Sheboygan Falls Unit 2 advanced gas path projects are expected to be completed in the second quarter of 2026.

Existing Wind Farm Refurbishment - In May 2025, the PSCW issued an order authorizing WPL to refurbish the Bent Tree wind farm.

In December 2025, the PSCW issued an order authorizing WPL to refurbish the Forward Wind Energy Center.

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.

New Solar - In 2024, IPL completed 400 MW of new solar generation projects in Iowa.

New Energy Storage - In 2024, IPL received approval from the IUC to construct, own and operate up to 99 MW of energy storage, which was placed in service in November 2025 at the site of its Wever solar facility.

In July 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 150 MW of energy storage at the site of its retired Lansing Generating Station.

In August 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 75 MW of energy storage at the site of its Golden Plains wind farm.

In September 2025, the IUC issued an order authorizing IPL to construct, own and operate up to 75 MW of energy storage at the site of its Whispering Willow - North wind farm.

New Natural Gas-fired Electric Generation - In June 2025, IPL received approval from the IUC to construct, own and operate the Cedar River Generating Station, a 94 MW natural gas-fired EGU using RICE technology, at the site of IPL’s Prairie Creek Generation Station.

In December 2025, IPL received an order from the IUC for approval to construct, own and operate an approximately 720 MW simple-cycle natural gas-fired EGU at the site of its Marshalltown Generating Station, known as the Bobcat Energy Center.

In January 2026, IPL received approval from the IUC to construct, own and operate a 94 MW natural gas-fired EGU using RICE technology at the site of its Burlington Generating Station.

New Wind - In July 2025, IPL filed for advance rate-making principles with the IUC for up to 1,000 MW of new wind generation in Iowa.

The advance rate-making principles filing included requests for a fixed cost cap of $3,020/kilowatt, including AFUDC and transmission upgrade costs among other costs, and a return on common equity of 11.25%.

In December 2025, IPL reached a non-unanimous settlement agreement with the Iowa Office of Consumer Advocate and others, subject to IUC approval, for up to 1,000 MW nameplate capacity of wind generation with a cost cap of $3,020/kW including AFUDC and transmission costs.

IPL’s return on common equity will be the same as other assets without advance rate-making principles for purposes of setting future rates and IPL’s blended return on common equity, which will be updated each year, will be used for IPL’s retail electric earnings sharing mechanism calculation.

A decision from the IUC is currently expected in the first half of 2026.

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

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(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 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.

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

Subsequent to December 31, 2025, IPL retired Prairie Creek Unit 1 and fuel switched Prairie Creek Unit 3 (65 MW in aggregate) to natural gas.

WPL currently plans to continue coal operations at Edgewater Unit 5 (414 MW) and Columbia Units 1 and 2 (595 MW in aggregate) at least through 2029, as well as evaluate the potential conversion of these EGUs 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 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:

• Exceeded its 2020 targets by reducing air emissions for sulfur dioxide by over 90%, nitrogen oxides by over 80% and mercury by over 90% from 2005 levels.

• 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.

• 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.

In addition, Alliant Energy’s environmental stewardship efforts include a goal to partner to plant more than 1 million trees by the end of 2030.

Future updates to sustainable energy plans and attaining these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories.

Refer to Note 3 for additional details on Columbia Units 1 and 2.

Environmental Stewardship - Alliant Energy’s environmental stewardship is focused on the implementation of a responsible energy strategy.

Alliant Energy’s strategy and business plans consider the transition to a low-carbon economy as one of several factors driving transformation of the energy industry.

Alliant Energy’s journey toward carbon reductions includes long-term voluntary goals to eliminate all coal-fired EGUs from its generating fleet by 2040 and aspiring to achieve net-zero GHG emissions from its utility operations by 2050.

Alliant Energy’s voluntary Environmental Stewardship goals previously included interim 2030 environmental-related goals for GHG emissions, utility water supply, and electrifying owned light-duty fleet vehicles.

In the first quarter of 2026, Alliant Energy decided to remove the interim 2030 voluntary environmental-related goals while remaining focused on its long-term voluntary goals.

This decision was made due to a combination of factors, including the need to serve its customers with affordable, safe, and reliable energy, resource adequacy requirements, and increasing customer energy needs.

Alliant Energy’s voluntary environmental stewardship goals may be revised, or their achievement may be delayed, based on increasing customer energy needs, reliability and resource adequacy requirements, and tax policy changes.

The ability to achieve these goals will depend on future economic developments, evolving energy technologies and emerging trends in Alliant Energy’s service territories.

These goals are not meant to be considered guidance.

Other Customer-focused Investments

Electric and Gas Distribution Systems - Customer-focused investments include replacing, modernizing and upgrading infrastructure in the electric and gas distribution systems.

Electric system investments will focus on areas such as improving reliability and resiliency with more underground electric distribution and enabling distributed energy solutions with higher capacity lines.

Gas system investments will focus on pipeline replacement to ensure safety and pipeline expansion to support reliability and economic development.

Electric system investments will focus on areas such as improving reliability and resiliency with more underground electric distribution and upgrades including automation and enabling distributed energy resources.

Gas system investments will focus on pipeline replacement to modernize Alliant Energy’s gas distribution systems and pipeline expansion to support reliability and economic development.

Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2026 through 2029 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.

Fiber Optic Telecommunication Network - Alliant Energy installed 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.

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.

Additionally, IPL expects to make investments in gas pipelines to serve new natural gas generating facilities.

Gas Pipeline Safety - The Pipeline and Hazardous Materials Safety Administration published various final rules from 2019 through 2024 that updated safety requirements for gas transmission pipelines, and updated procedures were implemented to address these rules.

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

Plans to address certain requirements for specific pipelines were developed and implemented.

The majority of identified remediation efforts have been completed with remaining items to be completed by July 2035.

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.

Technology - Alliant Energy, IPL and WPL currently plan to make investments in technology to enhance productivity and efficiency through automation, customer self-service and telework.

Technology - Alliant Energy, IPL and WPL currently plan to make investments in technology to enhance productivity and efficiency through automation and customer self-service.

Estimated capital expenditures for expected and current technology projects for 2026 through 2029 are included in the “Other” line in the construction and acquisition expenditures table in “ Liquidity and Capital Resources .”

Non-utility business - Alliant Energy continues to explore growth of its Travero businesses and other limited scope opportunities outside of, but complementary to, Alliant Energy’s core utility business.

This non-utility strategy continues to evolve through exploration of modest strategic opportunities that are accretive to earnings and cash flows.

Retail Base Rate Filings - Base rate changes reflect both returns on additions to infrastructure and recovery of changes in costs incurred or expected to be incurred to provide electric and gas service to retail customers.

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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;

• 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 totaling $52 million and $16 million in 2025 and 2024, respectively, 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;

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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.

IPL filed a subsequent proceeding with the IUC in December 2025 for its October 2024 through September 2025 forward-looking Test Period retail electric and gas rate reviews, which compared actual revenues and costs to those initially forecasted by IPL.

IPL currently does not expect any rate adjustments from this subsequent proceeding.

WPL’s Retail Electric and Gas Rate Reviews (2026/2027 Forward-looking Test Period) - In December 2025, the PSCW issued an order authorizing annual base rate increases of $69 million and $7 million for WPL’s retail electric and gas customers, respectively, effective January 1, 2026, for the 2026 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 energy storage.

The PSCW’s order also authorized WPL to implement an additional $75 million and $5 million increase in annual rates for its retail electric and gas customers, respectively, effective January 1, 2027, for the 2027 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 wind refurbishment projects, energy storage, existing natural gas-fired EGU improvements, solar generation costs incurred that exceed the construction cost estimates previously approved by the PSCW (refer to Note 3 for further discussion), and electric and gas distribution investments.

The order extends, with certain modifications, an earnings sharing mechanism through 2027.

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WPL must defer 50% of its excess earnings between 10.05% 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 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.

The PSCW also authorized an AFUDC applied to 100% of CWIP balances related to construction activity on capital projects requiring PSCW approval and are impacted by federal law changes.

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

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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.

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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

Tax Legislation

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

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 standalone investment tax credit for energy storage projects, and the right to transfer renewable tax credits generated after 2022 to other corporate taxpayers.

The legislation also established 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 Inflation Reduction Act of 2022 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.

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

In July 2025, the One Big Beautiful Bill Act was enacted, which modified various clean energy tax credits under the Inflation Reduction Act of 2022, including production tax credits and investment tax credits.

The most significant provisions of the new legislation for Alliant Energy, IPL, and WPL relate to the accelerated phase out of clean energy tax credits for eligible wind and solar projects for which construction begins more than 12 months after the enactment date or for projects placed in service after 2027, and restricted access to clean energy tax credits for projects that begin construction after 2025 and receive impermissible amounts of construction support from entities with ties to certain foreign countries, including China.

Additionally, in July 2025, the Presidential Administration directed the U.S.

Department of the Treasury to strictly enforce the termination of clean energy tax credits, including issuing new and revised guidance in August 2025, to ensure that requirements concerning the beginning of construction are not circumvented.

Refer to “ Customer Investments ” for discussion of Alliant Energy’s, IPL’s and WPL’s current plans to develop and/or acquire new renewable generation and energy storage projects.

Alliant Energy, IPL and WPL currently expect these planned renewable generation and energy storage projects would continue to be eligible for clean energy tax credits.

If these renewable generation and energy storage projects do not begin construction within the anticipated timeframes or fail to meet other eligibility requirements, the amount of clean energy tax credits could be significantly reduced, which could adversely impact Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations.

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

Economic Development

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.

Alliant Energy has various development-ready sites throughout Iowa, including the Prairie View Industrial Center Super Park in Ames, Iowa and the River City Industrial Center in Mason City, Iowa.

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 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 current and planned renewable generation and energy storage projects, including transferring tax credits from such projects to other corporate taxpayers.

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, energy storage and wind projects.

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.

Advance Rate-making Principles

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 GCU Certificate from the IUC in order to construct energy storage projects.

LIQUIDITY AND CAPITAL RESOURCES

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As summarized below, Alliant Energy, IPL and WPL believe they have the ability to generate and obtain adequate amounts of cash to meet their requirements and plans for cash in the next 12 months and beyond.

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.

Liquidity Position - At December 31, 2025, Alliant Energy had $556 million of cash and cash equivalents, $1,212 million ($550 million at the parent company, $262 million at IPL and $400 million at WPL) of available capacity under the single revolving credit facility and no 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, 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);

Long-term Debt (including current maturities) (LD);

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.

The following table shows financial capital structures as of December 31, 2025, as well as an adjusted capitalization structure that Alliant Energy believes is consistent with how a majority of the rating agencies currently view its junior subordinated notes:

Alliant Energy IPL WPL

(in millions) Actual Adjusted (a) Actual Actual

Common equity $7,334 $7,697 $4,844 $4,375

Long-term debt (including current maturities) 12,028 11,665 4,680 3,669

Short-term debt 88 88 88 —

Total capitalization $19,450 $19,450 $9,612 $8,044

Total debt $12,116 $11,753 $4,768 $3,669

Ratio of debt to total capitalization 62 % 60 % 50 % 46 %

(a) The long-term debt component of Alliant Energy’s financial capital structure includes junior subordinated notes classified as “Long-term debt, net” on Alliant Energy’s balance sheet (refer to Note 8(b) for additional information).

The adjusted presentation at December 31, 2025 attributes 50% of the junior subordinated notes to common equity and 50% to long-term debt, to align with the debt-to-capital ratio used by the majority of rating agencies.

The non-GAAP adjusted presentation reflecting this treatment is useful and relevant to investors in understanding how management and the rating agencies evaluate Alliant Energy’s capital structure.

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 at 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 and equity imputed by rating agencies, market conditions, the impact of tax initiatives and legislation, and any potential proceeds from asset sales.

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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.

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

Credit and Capital Markets - Alliant Energy, IPL and WPL maintain a single revolving credit facility to provide backstop liquidity to their commercial paper programs, and ensure a committed source of liquidity in the event the commercial paper market becomes disrupted.

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Alliant Energy IPL WPL

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

Higher collections from IPL’s and WPL’s retail electric and IPL’s gas base rate increases $339 $277 $62

Changes in income taxes paid/received (a) 69 (36) 95

Changes in levels of production fuel 19 2 17

Increased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales 62 35 27

Timing of WPL’s fuel-related cost recoveries from retail electric customers 56 — 56

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

Lower revenues at IPL due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism (122) (122) —

Changes in interest payments (66) (43) (13)

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

Changes in the sales of accounts receivable at IPL (51) (51) —

Lower revenues at IPL due to credits on customers’ bills through the tax benefit rider (36) (36) —

Changes in levels of materials and supplies (31) (8) (23)

Restructuring and voluntary employee separation payments in 2025 (25) (11) (12)

Lower revenues at IPL due to discontinuation of renewable energy rider in 2024 (24) (24) —

Lower wholesale revenues at IPL primarily due to lower sales from the expiration of IPL’s wholesale power agreement with Southern Minnesota Energy Cooperative in 2025 (22) (22) —

Other (primarily due to other changes in working capital) (147) (30) (117)

$300 $96 $183

(a) Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers in 2024 and 2025.

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

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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 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 IPL and WPL.

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

Alliant Energy, IPL and WPL currently intend to transfer all eligible renewable tax credits in the future.

Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $23 million, $3 million and $13 million of pension plan contributions in 2026, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2025 measurement date.

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(Higher) lower utility construction and acquisition expenditures (a) ($225) ($249) $24

Proceeds from sales of partial ownership interests in West Riverside in 2024 (123) — (123)

Changes in the amount of cash receipts on sold receivables 35 35 —

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($349) ($175) ($103)

(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.

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

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 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.

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 and the impact of tariffs, 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.

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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.

Construction and acquisition expenditures for 2026 through 2029 are currently anticipated as follows (in millions), which are focused on adding renewable generation and energy storage projects and dispatchable gas generation projects to meet growing customer demand for electricity, including expected future data center growth from currently executed electric service agreements, and strengthening the resiliency and reliability of the electric and gas distribution systems.

Alliant Energy, IPL and WPL are currently evaluating the impacts of tariffs, recently enacted legislation and additional potential demand from 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 utility business projects impacting construction and acquisition plans, and the related regulatory filings.

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Alliant Energy IPL WPL

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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.

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

Renewable Tax Credits - IPL and WPL started construction in 2024 and 2025, and currently expect to start construction in the first half of 2026, 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 2025 compared to 2024 (in millions):

Alliant Energy IPL WPL

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)

Higher (lower) net proceeds from issuance of long-term debt $857 $245 ($1)

Lower payments to retire long-term debt 509 200 —

Net changes in the amount of commercial paper outstanding (553) (12) (48)

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

Higher common stock dividends (29) (159) (11)

Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy — (40) 25

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FERC does not have authority over the issuance of securities by Alliant Energy, WPL, AEF or Corporate Services.

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

In January 2026, IPL received authorization from FERC to issue securities in 2026 and 2027 as follows (in millions):

Initial Authorization

Long-term debt securities issuances in aggregate $2,500

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State Regulatory Financing Authorizations - In March 2023, WPL received authorization from the PSCW to have up to $500 million of short-term borrowings and/or letters of credit outstanding at any time through the expiration date of WPL’s credit facility agreement.

As of December 31, 2024, WPL also had authority to issue up to $600 million of long-term debt securities in aggregate through December 2025 pursuant to a February 2023 PSCW order.

In January 2026, WPL received authorization from the PSCW to issue up to $2.8 billion of long-term debt securities in aggregate in 2026-2028.

Shelf Registrations - Alliant Energy, IPL and WPL have current shelf registration statements on file with the SEC for availability to issue unspecified amounts of securities through December 2026.

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Refer to “ Results of Operations ” for discussion of expected common stock dividends in 2026.

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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.

Common Stock Issuances - Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2024 and 2025, and “ Results of Operations ” for discussion of expected issuances of common stock in 2026 through 2029.

Short-term Debt - In December 2025, Alliant Energy, IPL and WPL amended and extended their single revolving credit facility agreement, which expires in December 2030 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 two extension options, which would each extend the maturity date by one year.

Subject to certain conditions, Alliant Energy, IPL and WPL may exercise one extension option, which would 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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Actual 59% 50% 47%

The debt component of the capital ratios includes, when applicable, long- and short-term debt (excluding non-recourse debt and hybrid securities to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), finance lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases.

The debt component of the capital ratios includes, when applicable, long- and short-term debt (excluding non-recourse debt and hybrid securities (e.g., junior subordinated notes) to the extent the total carrying value of such hybrid securities does not exceed 15% of consolidated capital of the applicable borrower), finance lease obligations, certain letters of credit, guarantees of the foregoing and new synthetic leases.

Unfunded vested benefits under qualified pension plans and sales of accounts receivable are not included in the debt-to-capital ratios.

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Long-term Debt - Refer to Note 8 (b) for discussion of issuances and retirements of long-term debt in 2025, and “ Results of Operations ” for discussion of expected issuances and retirements of long-term debt in 2026.

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 2024, IPL issued $350 million of 4.95% senior debentures due 2034 and $300 million of 5.45% senior debentures due 2054, a portion of which was used for the retirement of IPL’s $500 million 3.25% senior debentures, and the remainder was used for general corporate purposes.

In 2024, WPL issued $300 million of 5.375% green bond debentures due 2034, and an amount equal to or in excess of the net proceeds was disbursed for the development and acquisition of its solar EGUs.

In 2024, AEF entered into a $300 million variable rate term loan credit agreement, which amended and restated the term loan credit agreement that expired in March 2024, and retired the $300 million variable rate term loan credit agreement set forth therein.

In 2024, AEF issued $375 million of 5.40% senior notes due 2027, 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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Credit ratings and outlooks as of the date of this report are as follows:

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Standard & Poor’s Ratings Services Moody’s Investors Service

Alliant Energy:

Corporate/issuer A- Baa2

Corporate/issuer BBB+ Baa2

Commercial paper A-2 P-2

Senior unsecured long-term debt BBB N/A

Outlook Negative Stable

Corporate/issuer A- Baa1

Outlook Stable Stable

Corporate/issuer BBB+ Baa1

Commercial paper A-2 P-2

Senior unsecured long-term debt A- Baa1

Outlook Negative Stable

Senior unsecured long-term debt BBB+ Baa1

Outlook Stable Stable

Corporate/issuer A- Baa1

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Senior unsecured long-term debt A- Baa1

Outlook Negative Stable

Outlook Stable Stable

Standard & Poor’s Ratings Services and Moody’s Investors Service issued credit ratings of BBB+ and Baa2, respectively, for the senior notes issued by AEF in 2018, 2020, 2022, 2023 and 2024 (with Alliant Energy as guarantor).

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Refer to Note 5(b) for additional information regarding IPL’s sales of accounts receivable program.

Guarantees and Indemnifications - At December 31, 2024, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm, prior divestiture activities and transfers of renewable tax credits to other corporate taxpayers.

Guarantees and Indemnifications - At December 31, 2025, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm, prior divestiture activities, transfers of renewable tax credits to other corporate taxpayers and electric transmission infrastructure.

Refer to Note 1 6 (d) for additional information.

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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.

Alliant Energy, IPL and WPL maintain credit policies intended to minimize overall credit risk and actively monitor these policies to reflect changes and scope of operations.

Alliant Energy, IPL, and WPL conduct credit reviews for certain counterparties, and employ credit risk controls such as letters of credit, parental guarantees, master netting agreements and termination provisions.

Alliant Energy, IPL, and WPL conduct credit reviews for certain counterparties, and employ credit risk controls such as letters of credit, surety bonds, parental guarantees, master netting agreements and termination provisions.

Credit exposure is monitored, and when necessary, activity with a specific counterparty is limited until credit enhancement is provided.

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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 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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Income Taxes - Alliant Energy, IPL and WPL are subject to income taxes in various jurisdictions.

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Carryforward Utilization - Significant federal tax credit carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2025.

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.

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.

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 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 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 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 - 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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Regulated Operations - Long-lived assets within regulated operations are reviewed 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 the carrying value of its regulated property, plant and equipment that has been recently completed or is probable of being retired early, an impairment charge is recognized equal to the amount of the carrying value that was disallowed recovery.

If IPL or WPL is disallowed a full or partial return on the carrying value of its regulated property, plant and equipment that has been recently completed or is probable of being retired early, an impairment charge is recognized equal to the difference between the carrying amount of the asset and the present value of the future revenues expected from its regulated property, plant and equipment.

Refer to Note 3 for further discussion of Alliant Energy’s, IPL and WPL’s long-lived assets within their regulated operations.

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.

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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.

Future updates, including updates due to the enactment of the revised CCR Rule, could have a material impact on Alliant Energy’s, IPL’s and WPL’s financial condition and results of operations.

Refer to Note 1 3 for further discussion of AROs.

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Note 1 6 provides further discussion of contingencies assessed at December 31, 2025 that may have a material impact on financial condition and results of operations, including various pending legal proceedings, guarantees and indemnifications.

Retroactive Tariffs on Solar Cells and Modules - In August 2023, the U.S.

Department of Commerce (DOC) issued a final ruling that found solar cells and modules produced in certain Southeast Asian countries, including Cambodia, Malaysia, Thailand and Vietnam, using parts and components produced in China, were circumventing pre-existing antidumping and countervailing duties on China.

Consistent with a June 2022 Presidential Proclamation, the DOC issued rules granting duty-free treatment of solar cells and modules imported from these four countries as of June 2022 until June 2024.

In August 2025, the U.S.

Court of International Trade (CIT) ruled that this two-year duty suspension, as issued, was impermissible.

In September 2025, this ruling from the CIT was appealed to the Federal Circuit.

The CIT's order has been stayed pending appeal.

Alliant Energy, IPL and WPL continue to assess the potential impact of these tariffs on previously completed solar generation projects and are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing litigation.

QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

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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