What changed in this filing

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Item 7. Management’s Discussion and Analysis

2024-02-16 compared with 2023-02-24 · 278 added, 257 removed, 348 unchanged (61% of the section changed)

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Refer to MDA in the combined 2022 Form 10-K for details on certain financial information for 2022 compared to 2021.

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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 communities count on - affordably, safely, reliably, and sustainably.

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 is supported by a strategy focused on meeting the evolving expectations of customers while providing an attractive return for investors, and pursuing emerging technologies and safe, sustainable methods of energy production.

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

This strategy includes the following key elements:

Providing affordable energy solutions to 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 its existing customers and attract new customers to its service territories.

Key Highlights -

• Alliant Energy’s Clean Energy Blueprint, also known as its cleaner energy strategy, continues to add clean energy resources in Iowa and Wisconsin, which directly reinvests in the communities Alliant Energy serves through the addition of skilled jobs, economic development and increased tax revenue.

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

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

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

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

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

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

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

• In 2022, Alliant Energy’s wind generation was the highest in its history, which resulted in renewable tax credits and fuel cost savings for its customers.

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

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

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

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

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

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

• IPL’s renewable energy rider became effective February 26, 2020, which allows for annual adjustments to electric rates charged to IPL’s retail electric customers for actual renewable energy costs incurred to fund IPL’s 1,000 MW of wind EGUs placed in service in 2019 and 2020, and related tax benefits, including production tax credits, that are provided to its electric customers.

• Providing $35 million of billing credits to IPL’s retail electric customers beginning in the third quarter of 2020 through June 2021, largely driven by Federal Tax Reform benefits for customers.

• Significant fuel cost reductions achieved in 2021 and 2022 as a result of shortening the term of IPL’s DAEC PPA by 5 years.

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

• 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.

• Redemption of IPL’s 5.1% cumulative preferred stock in 2021.

• Levelized cost recovery mechanism for the remaining net book value of Edgewater Unit 5, which helps reduce customer costs in 2022 and 2023.

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

• In 2023, the U.S.

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

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

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

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

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

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

1) transitioning its generation portfolio to meet the growing interest of customers for reliable and sustainable sources of energy, 2) upgrading its electric and gas distribution systems to strengthen safety 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.

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

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

• Planned development and acquisition of additional renewable energy, including approximately 1,100 MW of solar generation at WPL with in-service dates in 2022-2024, approximately 275 MW of battery storage at WPL with in-service dates in 2024 and 2025, approximately 400 MW of solar generation at IPL with in-service dates in 2023 and 2024, and approximately 75 MW of battery storage at IPL with in-service dates in 2024.

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

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

• WPL’s completion of new solar generation in Wisconsin in 2022, including 150 MW in Wood County, 50 MW in Richland County, and 50 MW in Rock County.

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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 in the communities it serves.

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

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

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

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

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

Currently, approximately 27% of Alliant Energy’s electric distribution system is underground.

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

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

• 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.

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

Key Highlights -

• Alliant’s Energy’s economic development efforts resulted in being named a Top Utility in Economic Development by Site Selection Magazine for the fourth year in a row, and in 2022 being awarded the Chairman’s Award for Workforce Development Leadership by the Center for Energy Workforce Development.

• Alliant Energy has various development-ready sites throughout Iowa and Wisconsin, including the 1,300-acre Big Cedar Industrial Center Mega-site in Cedar Rapids, Iowa, and the 730-acre Prairie View Industrial Center Super Park in Ames, Iowa, which are rail-served ready-to-build manufacturing and industrial sites in close proximity to the regional airport and interstate freeways and access IPL’s electric services.

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

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

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

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RESULTS OF OPERATIONS

Results of operations include financial information prepared in accordance with GAAP as well as utility electric margins and utility gas margins, which are not measures of financial performance under GAAP.

Utility electric margins are defined as electric revenues less electric production fuel, purchased power and electric transmission service expenses.

Utility gas margins are defined as gas revenues less cost of gas sold.

Utility electric margins and utility gas margins are non-GAAP financial measures because they exclude other utility and non-utility revenues, other operation and maintenance expenses, depreciation and amortization expenses, and taxes other than income tax expense.

Management believes that utility electric and gas margins provide a meaningful basis for evaluating and managing utility operations since electric production fuel, purchased power and electric transmission service expenses and cost of gas sold are generally passed through to customers, and therefore, result in changes to electric and gas revenues that are comparable to changes in such expenses.

The presentation of utility electric and gas margins herein is intended to provide supplemental information for investors regarding operating performance.

These utility electric and gas margins may not be comparable to how other entities define utility electric and gas margin.

Furthermore, these measures are not intended to replace operating income as determined in accordance with GAAP as an indicator of operating performance.

Additionally, the table below includes EPS for Utilities and Corporate Services, ATC Holdings, and Non-utility and Parent, which are non-GAAP financial measures.

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

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

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

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

Income (Loss) EPS Income (Loss) EPS

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

The increase was primarily due to higher revenue requirements and AFUDC from WPL capital investments and higher electric and gas margins, including the impacts of temperatures.

These items were partially offset by higher depreciation expense.

Alliant Energy’s Non-utility and Parent net income decreased by $29 million in 2022 compared to 2021, primarily due to higher financing expense and the impact of the Iowa state income tax rate change.

Table of Co ntents

Operating income and a reconciliation of utility electric and gas margins to the most directly comparable GAAP measure, operating income, was as follows (in millions):

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

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

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

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Net Income Variances - The following items contributed to increased (decreased) net income for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

Changes in electric utility (Refer to details below )

($76) ($98) $22

Operating income $928 $795 $453 $460 $452 $308

Electric utility revenues $3,421 $3,081 $1,859 $1,752 $1,562 $1,329

Electric production fuel and purchased power expenses (830) (642) (383) (295) (447) (347)

Electric transmission service expense (573) (537) (407) (367) (166) (170)

Utility Electric Margin (non-GAAP) 2,018 1,902 1,069 1,090 949 812

Gas utility revenues 642 456 351 265 291 191

Cost of gas sold (389) (258) (206) (149) (183) (109)

Utility Gas Margin (non-GAAP) 253 198 145 116 108 82

Other utility revenues 49 49 46 46 3 3

Non-utility revenues 93 83 — — — —

Other operation and maintenance expenses (704) (676) (369) (362) (278) (268)

Depreciation and amortization expenses (671) (657) (381) (375) (283) (276)

Taxes other than income tax expense (110) (104) (57) (55) (47) (45)

Operating income $928 $795 $453 $460 $452 $308

Operating Income Variances - Variances between periods in operating income for 2022 compared to 2021 were as follows (in millions):

Alliant Energy IPL WPL

Total higher (lower) utility electric margin variance (Refer to details below) $116 ($21) $137

Total higher utility gas margin variance (Refer to details below) 55 29 26

Total higher other operation and maintenance expenses variance (Refer to details below) (28) (7) (10)

Total higher depreciation and amortization expense

Other 4 (2) (2)

Changes in gas utility (Refer to details below )

(102) (51) (51)

Changes in other utility 3 3 —

Changes in non-utility (3) — —

Changes in total revenues (178) (146) (29)

Operating expenses:

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

Changes in electric transmission service (Refer to details below )

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

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

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

Changes in taxes other than income taxes (5) — (5)

Changes in total operating expenses 193 137 49

Changes in operating income 15 (9) 20

Other income and deductions:

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

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

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

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

Changes in total other income and deductions (16) 7 4

Changes in income before income taxes (1) (2) 24

Changes in income taxes (Refer to Note 12 for details)

Changes in net income $17 $6 $30

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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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$1,584 $1,562 16,415 15,596 $240 $291 95,222 88,077

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Sales Trends and Temperatures - Alliant Energy’s retail electric sales volumes were unchanged in 2022 compared to 2021 primarily due to increases in sales volumes to residential and commercial customers caused by changes in temperatures, offset by decreases in sales volumes to industrial customers caused by maintenance outages and labor-related disruptions at certain large customers.

Alliant Energy’s retail gas sales volumes increased 14% in 2022 compared to 2021, primarily due to changes in temperatures and increases in the number of retail gas customers.

Estimated increases (decreases) to electric and gas margins from the impacts of temperatures were as follows (in millions):

Electric Margins Gas Margins

2022 2021 2022 2021

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

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

2023 2022 Change 2023 2022 Change

IPL ($1) $16 ($17) ($8) $5 ($13)

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Total Alliant Energy ($6) $26 ($32) ($14) $7 ($21)

Electric Sales for Resale - Electric sales for resale volume changes were largely due to changes in sales in the wholesale energy markets operated by MISO.

Electric Sales for Resale - Bulk Power and Other - Bulk power and other volume changes were due to changes in sales in the wholesale energy markets operated by MISO.

These changes are impacted by several factors, including the availability and dispatch of Alliant Energy’s EGUs and electricity demand within these wholesale energy markets.

Changes in sales for resale revenues were largely offset by changes in fuel-related costs, and therefore, did not have a significant impact on electric margins.

Changes in bulk power and other revenues were largely offset by changes in fuel-related costs, and therefore did not have a significant impact on operating income.

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.

Changes in these transportation/other revenues did not have a significant impact on gas margins.

Utility Electric Margin Variances - The following items contributed to increased (decreased) utility electric margins for 2022 compared to 2021 (in millions):

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Electric Utility Revenue Variances - The following items contributed to increased (decreased) electric utility revenues for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

Higher revenue requirements at WPL due to increasing rate base (a) $121 $— $121

Higher revenues at IPL due to changes in credits on customers’ bills related to excess deferred income tax benefits amortization through the tax benefit rider (offset by changes in income taxes) 11 11 —

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

($62) ($96) $34

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

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

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

Lower revenues at IPL related to changes in the renewable energy rider (mostly offset by changes in income taxes caused by higher production tax credits) (37) (37) —

Other (includes higher wholesale margins at WPL) 14 1 13

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

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

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

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

Other (15) (13) (2)

($76) ($98) $22

(a) In December 2021, the PSCW issued an order authorizing annual base rate increases of $114 million and $15 million for WPL’s retail electric and gas customers, respectively, covering the 2022/2023 forward-looking Test Period, which was based on a stipulated agreement between WPL and certain stakeholders.

The key drivers for the annual base rate increases include higher retail fuel-related costs in 2022, lower excess deferred income tax benefits in 2022 and 2023 compared to 2021, and revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation.

Retail electric rate changes were effective on January 1, 2022 and extend through the end of 2023.

Retail gas rate changes were effective on January 1, 2022 and extended through the end of 2022.

The higher fuel expense costs are recognized in electric margin and the lower amount of excess deferred income tax benefits is recognized as an increase in income tax expense.

Utility Gas Margin Variances - The following items contributed to increased (decreased) utility gas margins for 2022 compared to 2021 (in millions):

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

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

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

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

WPL estimates the increase (decrease) to electric utility revenues from amounts within the fuel monitoring range were approximately $6 million and ($6) million in 2023 and 2022, respectively.

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

Gas Utility Revenue Variances - The following items contributed to increased (decreased) gas utility revenues for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

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) $17 $17 $—

Higher revenue requirements at WPL due to increasing rate base (refer to (a) above) 17 — 17

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

($91) ($42) ($49)

Estimated changes in sales volumes caused by temperatures (21) (13) (8)

Other (includes higher sales in 2022) 11 6 5

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Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2022 compared to 2021 (in millions):

Alliant Energy IPL WPL

Higher energy efficiency expense at IPL (mostly offset by higher revenues) ($15) ($15) $—

Non-utility Travero (mostly offset by higher revenues) (9) — —

Higher revenue requirements at WPL (a) 8 — 8

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

Other (3) (1) (2)

($102) ($51) ($51)

Other Income and Deductions Variances - The following items contributed to (increased) decreased other income and deductions for 2022 compared to 2021 (in millions):

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

Electric Production Fuel and Purchased Power Expenses Variances - The following items contributed to (increased) decreased electric production fuel and purchased power expenses for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

Higher interest expense primarily due to financings completed in 2022 and 2021, and higher interest rates ($48) ($9) ($16)

Lower equity income from unconsolidated investments, net (refer to Not e 6 for details of a reduction recorded in 2022 related to the MISO return on equity complaint)

Higher AFUDC primarily due to changes in CWIP balances related to WPL’s solar generation 35 2 33

Other (refer to Note 13(a) for details of IPL’s qualified pension plan settlement losses)

Lower electric production fuel costs (a) $99 $52 $47

Lower purchased power expense (b) 152 7 145

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

(109) 42 (151)

Income Taxes - Refer to Note 12 for details of effective income tax rates, including the impact of Iowa tax reform in 2022.

Preferred Dividend Requirements of IPL - Refer to Note 8 for details of the redemption of IPL’s 5.1% cumulative preferred stock in 2021, including a $5 million non-cash charge recorded in 2021 related to this transaction.

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

$94 $101 ($8)

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

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

Electric Transmission Service Expense Variances - The following items contributed to (increased) decreased electric transmission service expense for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

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) )

($12) ($15) $3

($10) ($13) $3

Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

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

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

Other (1) (2) —

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

Lower incentive compensation expense $7 $4 $3

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

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

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

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

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 $250 million of common stock in 2023 through the distribution agreement for the sale from time to time of up to $225 million of common stock that was executed in December 2022, and its Shareowner Direct Plan.

Alliant Energy and its subsidiaries currently expect to issue up to $1.2 billion of long-term debt in 2023.

AEF has $400 million of long-term debt maturing in 2023.

• Financing Plans - Alliant Energy currently expects to issue up to $25 million of common stock in 2024 through its Shareowner Direct Plan.

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

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

• Common Stock Dividends - Alliant Energy announced a 6% increase in its targeted 2024 annual common stock dividend to $1.92 per share, which is equivalent to a quarterly rate of $0.48 per share, beginning with the February 2024 dividend payment.

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

• Higher Earnings on Increasing Rate Base - Alliant Energy and WPL currently expect an increase in earnings in 2023 compared to 2022 due to impacts from increasing revenue requirements related to investments in the utility business, including WPL’s solar investments.

• Other Operation and Maintenance Expenses - Alliant Energy, IPL and WPL currently expect a decrease in other operation and maintenance expenses in 2023 compared to 2022 largely due to cost reductions resulting from operating efficiencies.

• Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2023 compared to 2022 due to financings completed in 2022 and planned in 2023 as discussed above, as well as expected higher interest rates.

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

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

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

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

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

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

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

• Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2024 compared to 2023 due to financings completed in 2023 and planned in 2024 as discussed above.

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

CUSTOMER INVESTMENTS

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

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

These priorities include:

Clean Energy Blueprint

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

This strategy includes the planned development and acquisition of additional renewable energy, including approximately 1,100 MW of solar generation at WPL with in-service dates in 2022-2024, approximately 275 MW of battery storage at WPL with in-service dates in 2024 and 2025, approximately 400 MW of solar generation at IPL with in-service dates in 2023 and 2024 and approximately 75 MW of battery storage at IPL with in-service dates in 2024.

In order to support reliable and sustainable energy and meet the MISO’s new seasonal resource adequacy requirements, Alliant Energy, IPL and WPL continue to evaluate additional opportunities for renewable generation, distributed energy resources and natural gas resources, as well as repower existing wind farms.

Estimated capital expenditures for these planned projects for 2023 through 2026 are included in the “Renewables and battery storage” line in the construction and acquisition table in “ Liquidity and Capital Resources .” These estimates include current expectations for higher costs for various projects, as supply constraints and commodity inflation continue to be prevalent in the solar market.

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addition, Alliant Energy completed the construction and acquisition of approximately 1,200 MW of wind generation in aggregate (approximately 1,000 MW at IPL and approximately 200 MW at WPL) from 2018 through 2020.

WPL’s Solar Generation and Distributed Energy Resources - In June 2021, WPL received an order from the PSCW for its first CA authorizing WPL to acquire, own, and operate 675 MW of new solar generation in the following Wisconsin counties:

Grant (200 MW), Sheboygan (150 MW), Wood (150 MW), Jefferson (75 MW), Richland (50 MW) and Rock (50 MW).

In June 2022, WPL received an order from the PSCW for its second CA authorizing WPL to acquire, construct, own, and operate up to 414 MW of new solar generation in the following Wisconsin counties:

Dodge (150 MW), Waushara (99 MW), Rock (65 MW), Grant (50 MW) and Green (50 MW).

The Wood, Richland and Rock County projects were placed in service in 2022, and the remaining projects in the first and second CAs are expected to be placed in service in 2023 and 2024.

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

The retirement of these coal-fired EGUs supports Alliant Energy’s strategy, which is focused on meeting its customers’ energy needs in an affordable, safe, reliable and sustainable manner.

In September 2022, WPL filed a request with the PSCW for approval to construct, own and operate 175 MW of battery storage, with 100 MW and 75 MW at the Grant County and Wood County solar projects, respectively, with in-service dates in 2024.

In January 2023, WPL filed a request with the PSCW for approval to construct, own and operate approximately 99 MW of battery storage at the Edgewater Generating Station, with an in-service date in 2025.

IPL’s Solar Generation and Distributed Energy Resources - In November 2021, IPL filed for advance rate-making principles with the IUB for up to 400 MW of solar generation with in-service dates in 2023 and 2024 and 75 MW of battery storage in 2024.

The advance rate-making principles filing included requests for a fixed cost cap, including AFUDC and transmission upgrade costs among other costs, and a return on common equity of 11.40%, and proposed that a portion of the construction be financed by tax equity partners.

In September 2022, IPL provided the IUB with a summary of the Inflation Reduction Act of 2022, as well as an economic analysis indicating full ownership for these planned solar and battery storage projects is currently expected to result in more cost benefits for its customers compared to previous plans to utilize tax equity financing.

In November 2022, the IUB denied these advance rate-making principles filings and IPL requested reconsideration of the IUB’s decision.

In December 2022, the IUB issued an order granting reconsideration of 200 MW of solar generation, and denied reconsideration of the other 200 MW of solar generation and 75 MW of battery storage.

In January 2023, IPL filed additional information with the IUB related to the 400 MW of solar generation and 75 MW of battery storage, including a revised fixed cost cap of $1,845/kilowatt, based on updated materials, labor and shipping costs.

In addition, IPL filed a request for judicial review in January 2023 regarding the denial of advance rate-making principles for the other 200 MW of solar generation and 75 MW of battery storage.

In February 2023, the IUB issued an order stating that it will not issue a decision on the advance rate-making principles for the 200 MW of solar that was granted reconsideration until it receives clarity regarding its authority to issue the advance rate-making principles while the judicial review is also pending.

IPL believes these solar generation and battery storage projects are in the best interests of its customers, and if advance rate-making principles are not approved by the IUB or approval by the IUB is expected to be delayed, IPL may decide to proceed with constructing the solar generation and battery storage subject to other applicable approvals (such as a GCU Certificate), and seek recovery in future rate reviews.

The 400 MW of new solar generation and 75 MW of battery storage would help replace a portion of the energy and capacity expected to be eliminated with the planned retirement of the coal-fired Lansing Generating Station (275 MW) in the first half of 2023 and the reduction of energy and capacity resulting from the December 2021 fuel switch of the Burlington Generating Station (212 MW) from coal to natural gas.

In addition, IPL’s plans include additional renewables and distributed energy resources, including community solar and energy storage systems, to add energy and capacity.

New MISO Seasonal Resource Adequacy Process - In August 2022, FERC approved MISO’s proposal to change its resource adequacy process establishing capacity planning reserve margin and capacity accreditation requirements effective with the 2023/2024 MISO Planning Year, to help ensure the reliability of electricity in the MISO region.

The process will change from the current Summer-based annual construct to four distinct seasons to help ensure the continued reliability of the electric transmission grid throughout each year.

FERC’s approval also establishes planning reserve margin requirements for all market participants on a seasonal basis and determines a seasonal accredited capacity value for certain classes of generating resources, including higher accredited capacity for wind generation during the Spring, Fall and Winter seasons and higher accredited capacity for solar generation during the Summer season.

Alliant Energy, IPL and WPL are currently unable to predict with certainty the future outcome or impact of these matters, but plan to construct and/or acquire additional renewable, battery and natural gas resources to meet the requirements of the new seasonal resource adequacy process and have reflected the estimated capital expenditures for these projects in the “Renewables and battery storage” and “Other” Generation lines in the construction and acquisition table in “ Liquidity and Capital Resources .”

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Counterparty Option Amount and Timing

Wisconsin Public Service Corporation (WPSC) 100 MW were exercised January 2022 and are pending PSCW approval;

additionally, up to 100 MW may be exercised prior to May 16, 2024 subject to PSCW approval (a)

Madison Gas and Electric Company (MGE) 25 MW were exercised January 2022 and approved by the PSCW in December 2022;

additionally, up to 25 MW may be exercised prior to May 16, 2025 subject to PSCW approval

WEC Energy Group, Inc.

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

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

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

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

Electric cooperatives Approximately 60 MW were acquired January 2018

(a) Upon WPSC’s exercise of its options, WPL may exercise reciprocal options, subject to approval by the PSCW, to purchase up to 200 MW of any natural-gas combined-cycle EGU that either WPSC or its affiliated utility, Wisconsin Electric Power Company, places in service prior to May 2030.

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

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 the coal-fired Lansing Generating Station (275 MW) in the first half of 2023, and fuel switch or retire Prairie Creek Units 1 and 3 (65 MW in aggregate) by December 31, 2025.

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

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

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

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

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 CO2 emissions by 50% from its owned fossil-fueled EGUs and reduce electric utility water supply by 75% from 2005 levels, and transition 100% of its owned light-duty fleet vehicles to be electric, as well as partner to plant more than 1 million trees by the end of 2030.

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

• By 2050, achieve an aspirational goal of net-zero CO2 emissions from the electricity it generates.

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

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

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

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.

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Estimated capital expenditures for expected and current electric and gas distribution infrastructure projects for 2024 through 2027 are included in the “Electric and gas distribution systems” lines in the construction and acquisition expenditures table in “ Liquidity and Capital Resources .”

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 among financially disadvantaged customers and communities.

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

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Gas Pipeline Safety - The Pipeline and Hazardous Materials Safety Administration published various final rules from 2019 through 2022 that updated safety requirements for gas transmission pipelines, and updated procedures were implemented to address these rules.

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

WPL’s Retail Electric and Gas Rate Reviews (2022/2023 Forward-looking Test Period) - In December 2021, the PSCW issued an order authorizing annual base rate increases of $114 million and $15 million for WPL’s retail electric and gas customers, respectively, covering the 2022/2023 forward-looking Test Period, which was based on a stipulated agreement between WPL and certain stakeholders.

The key drivers for the annual base rate increases include higher retail fuel-related costs in 2022, lower excess deferred income tax benefits in 2022 and 2023 and revenue requirement impacts of increasing electric and gas rate base, including investments in solar generation.

In addition, the PSCW authorized WPL to receive a recovery of and a return on the remaining net book value of Edgewater Unit 5 through 2023.

Retail electric rate changes were effective on January 1, 2022 and extend through the end of 2023.

Retail gas rate changes were effective from January 1, 2022 through the end of 2022.

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

These retail gas rate changes were effective on January 1, 2023 and extend through the end of 2023.

WPL’s settlement extends, with certain modifications, an earnings sharing mechanism through 2023.

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

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

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

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

Under the earnings sharing mechanism, WPL will defer a portion of its earnings if its annual regulatory return on common equity exceeds 9.95% during the 2024/2025 Test Period.

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

Through 2023, any such deferral is required to be offset against the remaining net book value of Edgewater Unit 5, which is currently expected to be retired by June 1, 2025.

WPL’s Retail Fuel-related Rate Filing (2021 Forward-looking Test Period) - In August 2022, the PSCW authorized WPL to collect $37 million in 2023 from its retail electric customers, plus interest, for an under-collection of fuel-related costs incurred by WPL in 2021 that were higher than fuel-related costs used to determine rates for such period.

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

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

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

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

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

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

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

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

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

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

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

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

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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 Reviews - WPL currently expects to file a retail electric and gas rate review with the PSCW in the second quarter of 2023 for the 2024/2025 forward-looking Test Period.

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

Any rate changes granted from this pending request are expected to be effective on January 1, 2024, with a decision from the PSCW expected by the end of 2023.

IPL currently expects to file a retail electric and gas rate review with the IUB by the first half of 2024.

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

LEGISLATIVE MATTERS

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

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

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

The 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 currently expect to utilize various provisions of the new legislation to enhance the tax benefits expected from their announced solar and battery storage projects, including transferring the future tax credits from such projects to other corporate taxpayers and opting to retain full ownership of such projects instead of financing a portion of the projects with tax equity partners.

Compared to previous plans to utilize tax equity financing, 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 and battery storage projects.

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

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

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

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

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

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

In March 2020, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted.

The most significant provision of the CARES Act for Alliant Energy relates to an acceleration of refunds of existing alternative minimum tax credits to increase liquidity.

In 2020, Alliant Energy received $11 million of credits that otherwise would have been received in 2021 and 2022.

In addition, Alliant Energy deferred certain 2020 payroll taxes to 2021 and 2022.

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

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

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LIQUIDITY AND CAPITAL RESOURCES

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

Capital structures as of December 31, 2022 were as follows (Common Equity (CE);

Financial capital structures as of December 31, 2023 were as follows (Common Equity (CE);

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

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

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

Debt imputations by rating agencies include, among others, 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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Capital needed to retire debt and fund capital expenditures related to large strategic projects is expected to be met primarily through external financings.

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Cash Flows - Selected information from the cash flows statements was as follows (in millions):

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Cash, cash equivalents and restricted cash, December 31 $63 $24 $53 $15 $7 $5

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Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for 2023 compared to 2022 (in millions):

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Timing of WPL’s fuel-related cost recoveries from retail electric customers $200 $— $200

Changes in gas stored underground 104 45 59

Changes in income taxes paid/refunded 94 81 6

Changes in the sales of accounts receivable at IPL 85 85 —

Changes in interest payments (39) (10) (10)

Changes in levels of production fuel (19) (16) (3)

Changes in levels of gas stored underground (15) — (15)

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

Changes in income taxes paid/refunded (3) (11) (18)

Higher collections from WPL’s retail electric and gas base rate increases 121 — 121

Changes in cash collateral and deposit balances at Corporate Services 38 — —

Increased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales 17 10 7

Timing of intercompany payments and receipts — 28 35

Changes in interest payments (67) (2) (35)

Decreased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales (53) (30) (23)

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

Other (primarily due to other changes in working capital) 13 (79) 49

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Refer to Note 12 for discussion of the carryforward positions.

As discussed in “ Legislative Matters ,” the Inflation Reduction Act of 2022 provides the right to transfer future renewable tax credits to other corporate taxpayers, which is expected to result in future cash flows from operating activities for Alliant Energy, IPL and WPL beginning as early as 2023.

Pension Plan Contributions - Alliant Energy, IPL and WPL currently expect to make $12 million, $1 million and $10 million of pension plan contributions in 2023, respectively, based on the funded status and assumed return on assets for each plan as of the December 31, 2022 measurement date.

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.

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

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

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

Refer to Note 13(a) for discussion of pension plan contributions in 2023 and the current funded levels of pension plans.

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Changes in the amount of cash receipts on sold receivables (145) (145) —

Other 21 16 17

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

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

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

($468) ($541) $87

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

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

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

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

Changes may result from a number of reasons, including regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, 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 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.

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

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

As a result, they

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

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

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

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2024 2025 2026 2027 2024 2025 2026 2027 2024 2025 2026 2027

Renewables and battery storage $900 $1,205 $725 $1,060 $325 $625 $260 $670 $575 $580 $465 $390

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

Gas projects 120 325 610 500 55 135 310 125 15 125 295 375

Other 100 80 50 40 55 40 20 15 45 40 30 25

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$2,275 $1,980 $2,435 $2,365 $1,125 $905 $1,245 $825 $965 $885 $1,020 $1,335

Renewables and Battery Storage - Alliant Energy, IPL and WPL continue to evaluate potential impacts from cost pressures prevalent in the solar generation and battery storage markets on the timing and estimated costs for IPL’s and WPL’s planned development and acquisition of additional renewable energy, which could impact their anticipated future construction and acquisition expenditures.

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

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

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

Upon exercise of such options, WPL will receive proceeds from the sale.

Refer to “ Customer Investments ” for additional information, including timing for the actual and potential exercise of options.

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

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

Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for 2023 compared to 2022 (in millions):

Alliant Energy IPL WPL

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

Lower payments to retire long-term debt 125 — 250

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

Payments to redeem cumulative preferred stock of IPL in 2021 200 200 —

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

Higher payments to retire long-term debt (625) — (250)

(Higher) lower common stock dividends (28) 41 (8)

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Preferred stock issuances in aggregate 300

State Regulatory Financing Authorizations - In 2017, WPL received authorization from the PSCW to have up to $400 million of short-term borrowings and/or letters of credit outstanding at any time through the earlier of the expiration date of WPL’s credit facility agreement (including extensions) or December 2024.

In February 2023, WPL received authorization from the PSCW to issue up to $1.2 billion of long-term debt securities in aggregate through December 2025.

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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, 2023, WPL also had authority to issue up to $900 million of long-term debt securities in aggregate through December 2025 pursuant to a February 2023 PSCW order.

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

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

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Common Stock Issuances - Refer to Note 7 for discussion of common stock issuances by Alliant Energy in 2022 and 2023, and “ Results of Operations ” for discussion of expected issuances of common stock in 2024.

Short-term Debt - In 2021, Alliant Energy, IPL and WPL entered into a single revolving credit facility agreement, which expires in December 2026 and is discussed in Note 9(a) .

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

There are currently 13 lenders that participate in the credit facility, with respective commitments ranging from $20 million to $130 million.

Subject to certain conditions, Alliant Energy, IPL and WPL may exercise two extension options, each extending 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 $300 million, for a potential total commitment of $1.3 billion, subject to lender approval for Alliant Energy and subject to lender and regulatory approvals for IPL and WPL.

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The equity component of the capital ratios excludes accumulated other comprehensive income (loss).

Long-term Debt - Refer to Note 9(b) for discussion of issuances and retirements of long-term debt in 2022 and 2023, and “ Results of Operations ” for discussion of expected issuances of long-term debt in 2023.

In 2021, IPL issued $300 million of 3.1% senior debentures due 2051, and the net proceeds from the issuance were used by IPL to retire its cumulative preferred stock in 2021 and for general corporate purposes.

In 2021, WPL issued $300 million of 1.95% green bond debentures due 2031, and an amount in excess of the net proceeds was disbursed for the construction and development of WPL’s wind and solar EGUs.

Long-term Debt - Refer to Note 9(b) for discussion of issuances and retirements of long-term debt in 2023, and “ Results of Operations ” for discussion of expected issuances and retirements of long-term debt in 2024.

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

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

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

In 2022, AEF issued $350 million of 3.6% senior notes due 2032 and used the net proceeds to reduce Alliant Energy’s outstanding commercial paper and 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

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Commercial paper A-2 P-2

Senior unsecured long-term debt N/A N/A

Senior unsecured long-term debt BBB+ N/A

Outlook Stable Stable

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Outlook Stable Stable

Corporate/issuer A A3

Corporate/issuer A Baa1

Commercial paper A-1 P-2

Senior unsecured long-term debt A A3

Outlook Negative Negative

Senior unsecured long-term debt A Baa1

Outlook Negative 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 and 2023 (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, 2022, various guarantees and indemnifications are outstanding related to Alliant Energy’s cash equity ownership interest in a non-utility wind farm and prior divestiture activities.

Guarantees and Indemnifications - At December 31, 2023, 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.

Refer to Note 17(d) for additional information.

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

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WPL’s retail electric margins have exposure 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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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.

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 all 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, 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.

Distress in the financial markets could increase Alliant Energy’s, IPL’s and WPL’s credit risk.

Investment Price - Alliant Energy, IPL and WPL are exposed to investment price risk as a result of their investments in securities, largely related to securities held by their pension and OPEB plans.

Refer to Note 13(a) for details of the securities held by their pension and OPEB plans.

Refer to “ Critical Accounting Policies and Estimates ” for the impact on retirement plan costs of changes in the rate of returns earned by plan assets.

Investment Price - Alliant Energy, IPL and WPL are exposed to investment price risk as a result of their investments in securities, largely related to securities held by their pension and OPEB plans, as well as unconsolidated investments accounted for under the equity method of accounting.

Refer to Note 13(a) for details of the securities held by their pension and OPEB plans, and Note 6 for details of equity investments.

Refer to “ Critical Accounting Estimates ” for the impact on retirement plan costs of changes in the rate of returns earned by plan assets.

Interest Rate - Alliant Energy, IPL and WPL are exposed to risk resulting from changes in interest rates associated with variable-rate borrowings.

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

Assuming the impact of a hypothetical 100 basis point increase in interest rates on variable-rate borrowings and cash amounts outstanding under IPL’s sales of accounts receivable program at December 31, 2022, Alliant Energy’s, IPL’s and WPL’s annual pre-tax expense would increase by approximately $11 million, $1 million and $3 million, respectively.

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

Refer to Notes 5(b) and 9 for additional information on cash amounts outstanding under IPL’s sales of accounts receivable program, and short- and long-term variable-rate borrowings, respectively.

Refer to “ Critical Accounting Policies and Estimates ” for the impacts of changes in discount rates on retirement plan obligations and costs.

Critical Accounting Policies and Estimates - Alliant Energy’s, IPL’s and WPL’s financial statements are prepared in conformity with GAAP, which requires management to apply accounting policies, judgments and assumptions, and make estimates that affect results of operations and the amounts of assets and liabilities reported in the financial statements.

The following accounting policies and estimates are critical to the business and the understanding of financial results as they require critical assumptions and judgments by management.

Refer to “ Critical Accounting Estimates ” for the impacts of changes in discount rates on retirement plan obligations and costs.

Critical Accounting Estimates - Alliant Energy’s, IPL’s and WPL’s financial statements are prepared in conformity with GAAP, which requires management to apply accounting policies, judgments and assumptions, and make estimates that affect results of operations and the amounts of assets and liabilities reported in the financial statements.

The following accounting estimates are critical to the business and the understanding of financial results as they require critical assumptions and judgments by management.

The results of these assumptions and judgments form the basis for making estimates regarding the results of operations and the amounts of assets and liabilities that are not readily apparent from other sources.

Actual financial results may differ materially from estimates.

Management has discussed these critical accounting policies and estimates with the Audit Committee of the Board of Directors.

Refer to Note 1 for additional discussion of accounting policies and estimates used in the preparation of the financial statements.

Management has discussed these critical accounting estimates with the Audit Committee of the Board of Directors.

Refer to Note 1 for additional discussion of accounting estimates used in the preparation of the financial statements.

Regulatory Assets and Regulatory Liabilities - IPL and WPL are regulated by various federal and state regulatory agencies.

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Regulatory assets and regulatory liabilities are recognized in accordance with the rulings of applicable federal and state regulators, and future regulatory rulings may impact the carrying value and accounting treatment of regulatory assets and regulatory liabilities.

Note 2 provides details of the nature and amounts of regulatory assets and regulatory liabilities assessed at December 31, 2023.

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

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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.

Note 2 provides details of the nature and amounts of regulatory assets and regulatory liabilities assessed at December 31, 2022.

In May 2023, IPL retired the Lansing Generating Station.

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

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

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

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

Alliant Energy’s and IPL’s critical assumptions and judgments for 2022 include estimates of qualifying deductions for repairs expenditures and allocation of mixed service costs due to the impact of Iowa rate-making principles on such property-related differences.

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

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

Refer to Note 12 for further discussion of tax matters.

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

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to Iowa rate-making principles.

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

Carryforward Utilization - Significant federal tax credit carryforwards exist for Alliant Energy, IPL and WPL as of December 31, 2023.

Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards prior to their expiration.

Federal credit carryforwards generated from 2004 through 2008 are expected to be utilized within five years of expiration.

All other federal credit carryforwards are expected to be utilized more than five years before expiration.

Based on projections of current and future taxable income, Alliant Energy, IPL and WPL plan to utilize all of these carryforwards 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 2022 included IPL’s and WPL’s generating units subject to early retirement and WPL’s solar generation projects recently completed and under construction.

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

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

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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 IPL concluded that Lansing (expected to be retired in the first half of 2023), and Alliant Energy and WPL concluded that Edgewater Unit 5 (expected to be retired by June 1, 2025) and Columbia Units 1 and 2 (expected to be retired by June 1, 2026), met the criteria to be considered probable of abandonment as of December 31, 2022.

IPL and WPL are currently allowed a full recovery of and a full return on its respective EGUs from both its retail and wholesale customers, and as a result, Alliant Energy, IPL and WPL concluded that no impairment was required as of December 31, 2022.

Upon retirement of Lansing, which is currently expected in the first half of 2023, IPL anticipates reclassifying the remaining net book value, which was $233 million as of December 31, 2022, from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets.

Continued recovery of the remaining net book value of Lansing is expected to be addressed in future rate reviews.

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

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

Alliant Energy, 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, 2023.

Note 3 provides additional details of these assets anticipated to be retired early.

WPL’s Solar Generation Projects Recently Completed and Under Construction - As discussed in “ Customer Investments ,” WPL previously received authorization from the PSCW to acquire, construct, own and/or operate approximately 1,100 MW of new solar generation, which includes various projects in various Wisconsin counties.

In 2022, WPL completed the construction of three solar projects, and the remaining solar projects are currently expected to be placed in service in 2023 and 2024.

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 the solar generation projects recently completed or under construction, then an impairment charge is recognized.

In July 2021, WPL notified the PSCW that it expected estimated construction costs associated with approximately 675 MW of new solar generation will exceed amounts previously approved by the PSCW by approximately 7-10%.

In addition, the prior authorization received from the PSCW for approximately 1,100 MW of new solar generation assumed that a portion of the construction costs would be financed by a tax equity partner.

Following the enactment of the Inflation Reduction Act of 2022, WPL determined that retaining full ownership of the approximately 1,100 MW of new solar generation is expected to result in more cost benefits for its customers.

Alliant Energy and WPL no longer expect their solar generation project construction costs to be financed with capital from tax equity partners, which would result in higher rate base amounts compared to those previously approved by the PSCW for WPL’s planned approximately 1,100 MW of solar generation.

Alliant Energy and WPL concluded that there was not a probable disallowance of anticipated higher rate base amounts as of December 31, 2022 given construction costs were reasonably and prudently incurred and full ownership of WPL’s planned solar generation is expected to result in more cost benefits for WPL's customers.

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Unbilled Revenues - Unbilled revenues are primarily associated with utility operations.

Energy sales to individual customers are based on the reading of customers’ meters, which occurs on a systematic basis throughout the month.

Amounts of energy delivered to customers since the date of the last meter reading are estimated at the end of each reporting period and the corresponding estimated unbilled revenue is recorded.

The unbilled revenue is based on estimates of daily system demand volumes, customer usage by class, temperature impacts, line losses and the most recent customer rates.

Such process involves the use of various judgments and assumptions and significant changes in these judgments and assumptions could have a material impact on results of operations.

As of December 31, 2022, unbilled revenues related to Alliant Energy’s utility operations were $247 million ($ 132 million at IPL and $ 115 million at WPL).

Note 3 provides additional details on these EGUs.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Effective January 1, 2020 upon the adoption of the new accounting standard for credit losses, certain contingencies, such as Alliant Energy Resources, LLC’s guarantees of the partnership obligations of an affiliate of Whiting Petroleum, require estimation each reporting period of the expected credit losses on those contingencies.

These estimates require significant judgment and result in recognition of a credit loss liability sooner than the previous accounting standards, which required recognition when the contingency became probable and could be reasonably estimated based on then currently available information.

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

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

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

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

in the third quarter of 2022.

Note 1( l ) provides discussion of the adoption of the new accounting standard for credit losses.

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

Note 17 provides further discussion of contingencies assessed at December 31, 2023 that may have a material impact on financial condition and results of operations, including various pending legal proceedings, guarantees and indemnifications.

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

What changed 10-K

Item 7. Management’s Discussion and Analysis