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Item 8. Financial Statements and Supplementary Data

2022-02-18 compared with 2021-02-19 · 255 added, 279 removed, 1848 unchanged (22% of the section changed)

FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

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As of December 31, 2021, the Company had a recorded consolidated regulatory assets balance of $ 1,940 million and regulatory liabilities balance of $ 1,271 million.

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The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight.

The Company’s rates are subject to regulatory rate-setting processes and periodic earnings oversight.

The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital.

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• We tested the design and operating effectiveness of management’s controls over the evaluation of regulatory assets and liabilities, including the monitoring and evaluation of regulatory developments that may affect the likelihood of recovering costs in future rates or of a future reduction in rates.

• We inspected the Company’s analysis supporting the probability of recovery for regulatory assets or refund or future reduction in rates for regulatory liabilities not yet addressed in a regulatory order to assess the reasonability of management’s assertions.

• We obtained and evaluated the Company’s analysis supporting the probability of recovery for regulatory assets or refund or future reduction in rates for regulatory liabilities not yet addressed in a regulatory order to assess the reasonability of management’s assertions.

• We inquired of management regarding current events impacting the Company and inspected minutes of the board of directors and other committees of the Company and evaluated whether matters were identified that may have an impact on recorded regulatory asset and liability balances.

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We evaluated the external information and assessed whether there were matters in such information that would be contradictory to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.

• We obtained representation letters from management and evaluated such letters to assess whether information was present that would be relevant to the assessment of recovery of the Company’s regulatory assets or refund of regulatory liabilities.

• We inquired of management about property, plant, and equipment, net that may be abandoned.

We inspected minutes of the board of directors and other committees of the Company, regulatory orders and other filings with the regulatory agencies to identify evidence that may contradict management’s assertion regarding probability of an abandonment or that may have an impact on the recorded balances.

• We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.

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We have served as the Company’s auditor since 2002.

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ALLIANT ENERGY CORPORATION

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

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Retained earnings 3,250 2,994

Accumulated other comprehensive income (loss) ( 1 ) 1

Accumulated other comprehensive loss — ( 1 )

Shares in deferred compensation trust - 383,532 and 380,542 shares at a weighted average cost of $ 30.59 and $ 28.73 per share

( 12 ) ( 11 )

Total Alliant Energy Corporation common equity 5,990 5,688

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

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Accounts receivable ( 530 ) ( 468 ) ( 472 )

Derivative assets ( 142 ) ( 7 ) 2

Regulatory assets 51 ( 130 ) ( 16 )

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Deferred income taxes 193 171 54

Pension and other benefit obligations ( 137 ) 27 ( 25 )

DAEC PPA amendment buyout payment — ( 110 ) —

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Proceeds from issuance of common stock, net 28 247 390

Payments to redeem cumulative preferred stock of IPL ( 200 ) — —

Proceeds from issuance of long-term debt 600 1,250 950

Payments to retire long-term debt ( 8 ) ( 657 ) ( 256 )

Net change in commercial paper and other short-term borrowings 52 ( 104 ) 26

Net change in commercial paper 126 52 ( 104 )

Other ( 13 ) ( 27 ) ( 24 )

11 unchanged sentences

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

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Common stock dividends ($ 1.42 per share)

At-the-market offering program and Shareowner Direct Plan issuances 197 197

( 337 ) ( 337 )

Equity forward settlements and Shareowner Direct Plan issuances 390 390

Equity-based compensation plans and other 10 10

Other comprehensive income, net of tax 2 2

Other comprehensive loss, net of tax ( 1 ) ( 1 )

Ending balance 2 2,446 2,766 1 ( 10 ) 200 5,405

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Common stock dividends ($ 1.52 per share)

( 377 ) ( 377 )

Equity forward settlements and Shareowner Direct Plan issuances 247 247

Equity-based compensation plans and other 11 ( 1 ) 10

Adoption of new accounting standard, net of tax (refer to Note 1( l ) )

Other comprehensive loss, net of tax ( 2 ) ( 2 )

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Common stock dividends ($ 1.61 per share)

Equity forward settlements and Shareowner Direct Plan issuances 247 247

( 403 ) ( 403 )

Shareowner Direct Plan issuances 1 27 28

Equity-based compensation plans and other 18 ( 1 ) 17

Adoption of new accounting standard, net of tax (refer to Note 1(o) )

Other comprehensive loss, net of tax ( 2 ) ( 2 )

Redemption of IPL’s cumulative preferred stock ( 200 ) ( 200 )

Other comprehensive income, net of tax 1 1

Ending balance $ 3 $ 2,749 $ 3,250 $ — ($ 12 ) $ — $ 5,990

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Shareowners and the Board of Directors of Interstate Power and Light Company:

To the Shareowner and the Board of Directors of Interstate Power and Light Company:

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of Interstate Power and Light Company and subsidiary (the “Company”) as of December 31, 2020 and 2019, the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, 2020, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the “financial statements”).

We have audited the accompanying consolidated balance sheets of Interstate Power and Light Company and subsidiaries (the “Company”) as of December 31, 2021 and 2020, the related consolidated statements of income, equity, and cash flows, for each of the three years in the period ended December 31, 2021, and the related notes and the schedule listed in the Index at Item 15 (collectively referred to as the “financial statements”).

In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2021 and 2020, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2021, in conformity with accounting principles generally accepted in the United States of America.

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As of December 31, 2021, the Company had a recorded consolidated regulatory assets balance of $ 1,443 million and regulatory liabilities balance of $ 691 million.

The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight.

The Company’s rates are subject to regulatory rate-setting processes and periodic earnings oversight.

The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital.

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Future regulatory rulings may impact the carrying value and accounting treatment of the regulatory assets and regulatory liabilities.

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We identified the impact of rate regulation as a critical audit matter due to the significant judgments made by management to support its assertions about impacted account balances and disclosures and the high degree of subjectivity involved in assessing the impact of future regulatory orders on the financial statements.

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• We inquired of management about property, plant, and equipment, net that may be abandoned.

We inspected minutes of the board of directors and other committees of the Company, regulatory orders, and other filings with the regulatory agencies to identify evidence that may contradict management’s assertion regarding probability of an abandonment or that may have an impact on the recorded balances.

• We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.

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We have served as the Company’s auditor since 2002.

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INTERSTATE POWER AND LIGHT COMPANY

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

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Current liabilities:

Current maturities of long-term debt $ — $ 200

Accounts payable $ 173 $ 162

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Total current liabilities 455 447

Long-term debt, net (excluding current portion) 3,345 2,947

Long-term debt, net 3,643 3,345

Other liabilities:

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

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Equity component of allowance for funds used during construction ( 7 ) ( 17 ) ( 35 )

Other 11 12 1

Other changes in assets and liabilities:

Accounts receivable ( 539 ) ( 466 ) ( 467 )

Derivative assets ( 55 ) ( 7 ) ( 5 )

Regulatory assets 30 ( 93 ) ( 11 )

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Deferred income taxes 62 79 35

Pension and other benefit obligations ( 59 ) 18 ( 11 )

DAEC PPA amendment buyout payment — ( 110 ) —

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Net cash flows from (used for) operating activities 153 ( 6 ) 173

Cash flows used for investing activities:

Cash flows from (used for) investing activities:

Construction and acquisition expenditures ( 384 ) ( 687 ) ( 1,020 )

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Other ( 27 ) ( 72 ) ( 60 )

Net cash flows used for investing activities ( 301 ) ( 667 ) ( 430 )

Cash flows from financing activities:

Net cash flows from (used for) investing activities 91 ( 301 ) ( 667 )

Cash flows from (used for) financing activities:

Common stock dividends ( 400 ) ( 236 ) ( 168 )

Capital contributions from parent 50 404 125

Payments to redeem cumulative preferred stock ( 200 ) — —

Proceeds from issuance of long-term debt 300 400 600

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Other ( 10 ) ( 20 ) ( 16 )

Net cash flows from financing activities 348 491 440

Net cash flows from (used for) financing activities ( 260 ) 348 491

Net increase (decrease) in cash, cash equivalents and restricted cash ( 16 ) 41 ( 3 )

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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INTERSTATE POWER AND LIGHT COMPANY

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Capital contributions from parent 50 50

Redemption of cumulative preferred stock ( 200 ) ( 200 )

Ending balance $ 33 $ 2,807 $ 929 $ — $ 3,769

Refer to accompanying Combined Notes to Consolidated Financial Statements.

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REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

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As of December 31, 2021, the Company had a recorded consolidated regulatory assets balance of $ 497 million and regulatory liabilities balance of $ 580 million.

The Company’s rates are subject to regulatory rate-setting processes and annual earnings oversight.

The Company’s rates are subject to regulatory rate-setting processes and periodic earnings oversight.

The regulation of rates is premised on the full recovery of prudently incurred costs and a reasonable rate of return on invested capital.

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Future regulatory rulings may impact the carrying value and accounting treatment of the regulatory assets and regulatory liabilities.

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• We inquired of management about property, plant, and equipment, net that may be abandoned.

• We evaluated the Company’s disclosures related to the impacts of rate regulation and regulatory developments, including disclosures related to the regulatory balances recorded.

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We have served as the Company’s auditor since 2002.

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WISCONSIN POWER AND LIGHT COMPANY

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

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Regulatory liabilities 478 484

Finance lease obligations - Sheboygan Falls Energy Facility 42 51

Pension and other benefit obligations 159 222

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

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Other changes in assets and liabilities:

Derivative assets ( 87 ) — 6

Regulatory liabilities ( 67 ) ( 93 ) ( 42 )

Deferred income taxes 132 90 20

Pension and other benefit obligations ( 63 ) 11 ( 7 )

Other ( 20 ) ( 32 ) ( 35 )

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Common stock dividends ( 168 ) ( 160 ) ( 144 )

Capital contribution from parent 25 125 200

Capital contributions from parent 245 25 125

Proceeds from issuance of long-term debt 300 350 350

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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WISCONSIN POWER AND LIGHT COMPANY

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Refer to accompanying Combined Notes to Consolidated Financial Statements.

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ALLIANT ENERGY CORPORATION

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energy holding company, whose primary wholly-owned subsidiaries are IPL, WPL, AEF and Corporate Services.

IPL’s financial statements include the accounts of IPL and its consolidated subsidiary, IPL SPE LLC, which is used for IPL’s sales of accounts receivable program.

IPL’s financial statements include the accounts of IPL and its consolidated subsidiaries, including IPL SPE LLC, which is used for IPL’s sales of accounts receivable program.

IPL is a direct subsidiary of Alliant Energy and is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa.

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WPL also sells electricity to wholesale customers in Wisconsin.

AEF is comprised of Travero (formerly known as Transportation), ATI, a non-utility wind farm, the Sheboygan Falls Energy Facility and other non-utility holdings.

AEF is comprised of Travero, ATI, corporate venture investments, a non-utility wind farm, the Sheboygan Falls Energy Facility and other non-utility holdings.

Travero includes a short-line rail freight service in Iowa;

a barge, rail and truck freight terminal on the Mississippi River;

and freight brokerage and logistics management services.

a Mississippi River barge, rail and truck freight terminal in Illinois;

freight brokerage services;

and a rail-served warehouse in Iowa, which began operations in 2021.

ATI, a wholly-owned subsidiary of AEF, holds all of Alliant Energy’s interest in ATC Holdings.

Corporate venture investments includes various minority ownership interests in regional and national venture funds, including a coalition with different energy companies across the U.S., working together to help identify and research innovative products, technologies and business models within the emerging energy economy.

The non-utility wind farm includes a 50 % cash equity ownership interest in a 225 MW wind farm located in Oklahoma.

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In March 2020, COVID-19 was declared a global pandemic, which has resulted in widespread travel restrictions, closures of commercial spaces and industrial facilities, and more people working from home in Alliant Energy’s service territories.

For 2020, Alliant Energy, IPL and WPL considered the impact of COVID-19 on their overall business operations, financial condition, results of operations and cash flows, along with assumptions and estimates used.

While the total expected impact of COVID-19 on future sales is currently unknown, Alliant Energy, IPL and WPL have experienced higher electric residential sales and lower electric commercial and industrial sales since the outset of the pandemic.

For 2020 and 2021, Alliant Energy, IPL and WPL considered the impact of COVID-19 on their overall business operations, financial condition, results of operations and cash flows, along with assumptions and estimates used.

In 2020, Alliant Energy, IPL and WPL experienced higher electric residential sales and lower electric commercial and industrial sales as a result of the pandemic.

In 2021, changes in COVID-19 impacts resulted in lower electric residential sales and higher electric commercial and industrial sales.

The degree to which the COVID-19 pandemic may impact Alliant Energy, IPL and WPL in the future is currently unknown and will depend on future developments of the pandemic as well as possible additional actions by government and regulatory authorities.

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NOTE 1 (b) Regulatory Assets and Regulatory Liabilities - Alliant Energy, IPL and WPL are subject to regulation by FERC and various state regulatory commissions.

As a result, Alliant Energy, IPL and WPL are subject to GAAP provisions for regulated operations, which provide that rate-regulated public utilities record certain costs and credits allowed in the rate-

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making process in different periods than for non-utility entities.

Regulatory assets generally represent incurred costs that have been deferred as such costs are probable of recovery in future customer rates.

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Changes in deferred tax assets and liabilities associated with certain property-related differences at IPL are accounted for differently than other subsidiaries of Alliant Energy due to rate-making practices in Iowa.

Rate-making practices in Iowa do not include the impact of certain deferred tax expenses (benefits) in the determination of retail rates.

Rate-making practices in Iowa do not allow the impact of certain deferred tax expenses (benefits) to be included in the determination of retail rates.

Based on these rate-making practices, deferred tax expense (benefit) related to these property-related differences at IPL is not recorded in the income statement but instead recorded to regulatory assets or regulatory liabilities until these temporary differences reverse.

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NOTE 1 (d) Cash, Cash Equivalents and Restricted Cash - Cash and cash equivalents include short-term liquid investments that have original maturities of less than 90 days.

At December 31, 2020, Alliant Energy’s and IPL’s cash and cash equivalents included $ 44 million and $ 44 million of money market fund investments, with interest rates of 0.04 % and 0.04 %, respectively.

At December 31, 2020 and 2019, restricted cash primarily related to requirements in Sheboygan Power, LLC’s debt agreement.

At December 31, 2021, Alliant Energy’s and IPL’s cash and cash equivalents included $ 32 million of money market fund investments, with an interest rate of 0.04 %.

At December 31, 2021 and 2020, Alliant Energy’s restricted cash related to requirements in Sheboygan Power, LLC’s debt agreement.

NOTE 1 (e) Property, Plant and Equipment -

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The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows:

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2021 2020 2019 2021 2020 2019

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In accordance with their respective regulatory commission decisions, IPL applies its AFUDC rates to 100 % of applicable CWIP balances and WPL generally applies its AFUDC rates to 50 % of applicable CWIP balances.

WPL may apply its AFUDC rates to 100 % of the retail portion of the CWIP balances for construction projects requiring a CA or CPCN that were approved by the PSCW after its then most recent rate order, including West Riverside.

Non-utility and Other Property -

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Taxes Collected from Customers - Sales or various other taxes collected by certain of Alliant Energy’s subsidiaries on behalf of other agencies are recorded on a net basis and are not included in revenues.

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Other - Alliant Energy, IPL and WPL do not disclose the value of unsatisfied performance obligations for:

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Cost of Gas Sold - Costs are incurred for the purchase, transportation and storage of natural gas to serve IPL’s and WPL’s gas customers and the costs associated with the natural gas delivered to customers are charged to “Cost of gas sold” in the income statements.

The tariffs for IPL’s and WPL’s retail gas customers provide for subsequent adjustments to their rates

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each month for changes in the cost of gas sold.

The tariffs for IPL’s and WPL’s retail gas customers provide for subsequent adjustments to their rates periodically for changes in the cost of gas sold.

Changes in the under-/over-collection of these costs are also recognized in “Cost of gas sold” in the income statements.

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Property, Plant and Equipment of Regulated Operations - Property, plant and equipment of regulated operations are reviewed for possible impairment whenever events or changes in circumstances indicate all or a portion of the carrying value of the assets may be disallowed for rate-making purposes.

If IPL or WPL are disallowed recovery of any portion of the carrying value of their regulated property, plant and equipment that is under construction, has been recently completed or is probable of abandonment, or conclude it is probable recovery will be disallowed, an impairment charge is recognized equal to the amount of the carrying value that was disallowed or is probable of being disallowed.

If IPL or WPL are only allowed a partial return on the carrying value of their regulated property, plant and equipment that is under construction, has been recently completed or is probable of abandonment, or conclude it is probable a full return will not be allowed, an impairment charge is recognized equal to the difference between the carrying value and the present value of the future revenues expected from their regulated property, plant and equipment.

If IPL or WPL are disallowed recovery of any portion of, or are only allowed a partial return on, the carrying value of their regulated property, plant and equipment that is under construction, has been recently completed or is probable of abandonment, or conclude it is probable recovery or a full return will be disallowed, then an impairment charge is recognized.

Property, Plant and Equipment of Non-utility Operations - Property, plant and equipment of non-utility operations are reviewed for possible impairment whenever events or changes in circumstances indicate the carrying value of the assets may not be recoverable.

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The liability is accreted to its present value and the capitalized cost is depreciated over the useful life of the related asset.

Accretion and depreciation expenses related to AROs for IPL’s and WPL’s regulated

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operations are recorded to regulatory assets on the balance sheets.

Accretion and depreciation expenses related to AROs for IPL’s and WPL’s regulated operations are recorded to regulatory assets on the balance sheets.

Revisions in estimated cash flows for IPL’s and WPL’s regulated operations are recorded as an increase or decrease to the ARO liability, with an offset to the asset cost, unless the asset is already retired and then the offset is recorded to regulatory assets or regulatory liabilities on the balance sheets.

Upon regulatory approval to recover IPL’s AROs expenditures, its regulatory assets are amortized to depreciation and amortization expenses in Alliant Energy’s and IPL’s income statements over the same time period the ARO expenditures are recovered from IPL’s customers.

WPL’s regulatory assets related to AROs are recovered as a component of depreciation rates pursuant to PSCW and FERC orders.

Accretion and depreciation expenses related to AROs for Alliant Energy’s non-utility operations are recorded to depreciation and amortization expenses in Alliant Energy’s income statements.

Upon settlement of the ARO liability, an entity settles the obligation for its recorded amount or incurs a gain or loss.

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The current expected credit losses for short-term trade receivables are based on estimates of losses resulting from the inability of customers to make required payments.

The methodology used to estimate losses is based on historical write-offs, regional economic conditions, significant events that could impact collectability, such as impacts related to COVID-19, the derecho windstorm and related regulatory actions, and forecasted changes to the accounts receivable aging portfolio and write-offs.

The methodology used to estimate losses is based on historical write-offs, regional economic conditions, significant events that could impact collectability, such as impacts related to COVID-19, significant weather related matters including the derecho windstorm and related regulatory actions, and forecasted changes to the accounts receivable aging portfolio and write-offs.

The current expected credit losses related to guarantees of the performance by third parties are estimated using both quantitative and qualitative information, which utilizes potential outcomes in a range of possible estimated amounts.

In 2016, the Financial Accounting Standards Board issued an accounting standard requiring use of a current expected credit loss model rather than an incurred loss method, which is intended to result in more timely recognition of credit losses on trade receivables, certain other assets and off-balance sheet credit exposures.

Alliant Energy, IPL and WPL adopted this standard on January 1, 2020 using a modified retrospective method of adoption, which required cumulative effect adjustments to retained earnings on January 1, 2020.

IPL and WPL did not record a cumulative effect adjustment to retained earnings and Alliant Energy recorded a pre-tax $ 12 million (after-tax $ 9 million) cumulative effect adjustment to decrease retained earnings related to Alliant Energy’s guarantees in the partnership obligations of an affiliate of Whiting Petroleum (refer to Note 17(d) for further discussion).

This adjustment is included in “Adoption of new accounting standard” in Alliant Energy’s equity statement for 2020.

NOTE 1 (m) Variable Interest Entities - An entity is considered a VIE if its equity investors do not have sufficient equity at risk for the entity to finance its activities without additional subordinated financial support from other parties, the entity is structured with disproportionate voting rights and substantially all of the entity’s activities are conducted on behalf of the investor with disproportionately fewer voting rights, or its equity investors lack any of the following characteristics:

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For finance leases, the rate implicit in the lease, if known, is used to determine the present value of the lease payments.

If the rate implicit in the lease is not known, the incremental borrowing rate is used to determine the present value of the lease payments.

Lease terms include options to extend or terminate the lease when it is reasonably certain that the option will be exercised.

Operating lease expense is recognized on a straight-line basis over the expected lease term.

Finance lease expense is comprised of depreciation and interest expenses.

Finance lease assets are depreciated on a straight-line basis over the shorter of the useful life of the underlying asset or the lease term.

NOTE 1 (o) New Accounting Standards -

Credit Losses - In 2016, the Financial Accounting Standards Board issued an accounting standard requiring use of a current expected credit loss model rather than an incurred loss method, which is intended to result in more timely recognition of credit losses on trade receivables, certain other assets and off-balance sheet credit exposures.

This adjustment is included in “Adoption of new accounting standard” in Alliant Energy’s equity statement for 2020.

Finance lease expense is comprised of depreciation and amortization, and interest expenses.

Finance lease assets related to leased land for solar generation are amortized on a straight-line basis over the lease term, and are accounted for as operating leases for rate-making purposes.

All other finance lease assets are depreciated on a straight-line basis over the shorter of the useful life of the underlying asset or the lease term.

REGULATORY MATTERS

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At December 31, regulatory assets were comprised of the following items (in millions):

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Alliant Energy IPL WPL

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WPL’s Western Wisconsin gas distribution expansion investments 52 55 — — 52 55

Commodity cost recovery 42 4 2 1 40 3

Derivatives 8 26 4 13 4 13

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At December 31, 2021, IPL and WPL had $ 75 million and $ 13 million, respectively, of regulatory assets that were not earning a return.

IPL’s regulatory assets that were not earning a return consisted primarily of retired analog electric meters, emission allowances, clean air compliance projects and debt redemption costs.

WPL’s regulatory assets that were not earning a return consisted primarily of costs for future expansion projects and environmental-related costs.

IPL’s regulatory assets that were not earning a return consisted primarily of retired analog electric meters, emission allowances and costs for certain construction projects.

WPL’s regulatory assets that were not earning a return consisted primarily of amounts related to the wholesale portion of under-collected costs, and costs for future expansion projects.

The other regulatory assets reported in the above table either earn a return or the cash has not yet been expended, in which case the assets are offset by liabilities that also do not incur a carrying cost.

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Pension and OPEB costs are included within the recoverable cost of service component of rates charged to IPL’s and WPL’s retail and wholesale customers, which are based upon pension and OPEB costs determined in accordance with GAAP and are calculated in accordance with IPL’s and WPL’s respective regulatory jurisdictions.

AROs - Alliant Energy, IPL and WPL believe it is probable that certain differences between expenses accrued for legal AROs related to their utility operations and expenses recovered currently in rates will be recoverable in future rates, and are deferring the differences as regulatory assets.

AROs - Alliant Energy, IPL and WPL believe it is probable that certain differences between expenses accrued for AROs related to their utility operations and expenses recovered currently in rates will be recoverable in future rates, and are deferring the differences as regulatory assets.

Assets retired early - IPL and WPL have retired various natural gas- and coal-fired EGUs, and IPL has retired certain analog electric meters.

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IPL’s DAEC PPA Amendment - In September 2020, IPL made a buyout payment of $ 110 million in exchange for shortening the term of its DAEC PPA by 5 years.

The payment was recorded as a reduction to “Other current liabilities” on Alliant Energy’s and IPL’s balance sheets and was included in “DAEC PPA amendment buyout payment” in Alliant Energy’s and IPL’s

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cash flows used for operating activities in 2020.

The buyout payment, including a return on, will be recovered from IPL’s retail and wholesale customers from 2021 through the end of 2025.

The payment was included in “DAEC PPA amendment buyout payment” in Alliant Energy’s and IPL’s cash flows used for operating activities in 2020.

The buyout payment, including a return on, will be recovered from IPL’s retail and wholesale customers from 2021 through the end of 2025, and is currently being amortized to “Electric production fuel and purchased power” in Alliant Energy’s and IPL’s income statements.

WPL’s Western Wisconsin gas distribution expansion investments - WPL made contributions in aid of construction to a third party for investments as part of its Western Wisconsin gas distribution expansion project.

Pursuant to authorization by the PSCW, Alliant Energy and WPL have recorded a regulatory asset for these costs, and are authorized by the PSCW to recover these amounts from WPL’s retail gas customers in base rates beginning in 2021.

Commodity cost recovery - Refer to Note 1(g) for details of IPL’s and WPL’s commodity cost recovery mechanisms.

The cost recovery mechanism for WPL’s retail electric customers is based on forecasts of certain fuel-related costs expected to be incurred during forward-looking test periods and fuel monitoring ranges determined by the PSCW during each retail electric rate proceeding or in a separate fuel cost plan approval proceeding.

In 2021, WPL’s actual fuel-related costs fell outside these fuel monitoring ranges, resulting in a $ 37 million deferral as of December 31, 2021.

Derivatives - In accordance with IPL’s and WPL’s fuel and natural gas recovery mechanisms, prudently incurred costs from derivative instruments are recoverable from customers in the future after any losses are realized, and gains from derivative instruments are refundable to customers in the future after any gains are realized.

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Cost of removal obligations 384 367 252 238 132 129

Derivatives 166 28 77 25 89 3

Electric transmission cost recovery 51 68 27 39 24 29

WPL’s West Riverside liquidated damages 36 38 — — 36 38

Derivatives 28 20 25 17 3 3

Other 49 73 23 43 26 30

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These rules limit the rate at which these tax benefits are allowed to be passed on to customers.

Cost of removal obligations - Alliant Energy, IPL and WPL collect in rates future removal costs for many assets that do not have associated legal AROs.

In 2021, Alliant Energy’s, IPL’s and WPL’s tax-related regulatory liabilities decreased primarily due to returning a portion of these excess deferred tax benefits back to customers.

Cost of removal obligations - Alliant Energy, IPL and WPL collect in rates future removal costs for many assets that do not have associated AROs or that have removal costs in addition to AROs.

Alliant Energy, IPL and WPL record a regulatory liability for the amounts collected in rates for these future removal costs and reduce the regulatory liability for amounts spent on removal activities.

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Electric transmission cost recovery - Refer to Note 1(g) for details of IPL’s and WPL’s electric transmission cost recovery mechanisms.

In 2020, pursuant to a June 2020 IUB order, IPL issued $ 42 million of credits to its retail electric customers through its transmission cost rider for amounts previously collected in rates, which resulted in a reduction in regulatory liabilities and a corresponding reduction to “Electric transmission service” expense in Alliant Energy’s and IPL’s income statements during 2020.

Refer to Note 17(g) for discussion of refunds received by IPL and WPL in 2020 related to MISO transmission owner return on equity complaints, which were recorded to regulatory liabilities in 2020.

In 2020, pursuant to an IUB order, IPL issued $ 42 million of credits to its retail electric customers through its transmission cost rider for amounts previously collected in rates, which resulted in a reduction to “Electric transmission service” expense in Alliant Energy’s and IPL’s income statements in 2020.

WPL’s West Riverside liquidated damages - Pursuant to terms included in the related West Riverside construction procurement contracts, WPL reached agreement with the contractor on liquidated damages in 2020.

A significant portion of the liquidated damages was settled by WPL offsetting amounts owed to the contractor that were previously withheld for payment, which were non-cash investing activities.

In December 2020, the PSCW authorized WPL to record the liquidated damages as a regulatory liability, which is expected to be returned to WPL’s customers as determined in future regulatory proceedings.

In December 2020, the PSCW authorized WPL to record the liquidated damages as a regulatory liability, which the PSCW authorized to be returned to WPL’s retail customers in 2022 and 2023.

Derecho Windstorm - In August 2020, a derecho windstorm caused considerable damage to IPL’s electric distribution system in its service territory, and over 250,000 of its customers lost power.

IPL completed its initial restoration and rebuilding efforts in August 2020 and permanent repairs to the system will continue into 2021.

IPL’s current estimate of the total cost of the windstorm is approximately $ 140 million, and as of December 31, 2020, approximately $ 135 million was recorded substantially to “Property, plant and equipment, net” on Alliant Energy’s and IPL’s balance sheets.

In December 2020, IPL received approval from the IUB for utilization of a regulatory account to track certain incremental costs and benefits incurred resulting from the windstorm until IPL’s next rate proceeding.

Tax benefits and the incremental operation and maintenance expenses

Table of Cont ents

resulting from the windstorm were deferred and recorded as a net regulatory liability of $ 7 million as of December 31, 2020, which is included in “Other” regulatory liabilities in the above table.

IPL completed its initial restoration and rebuilding efforts in August 2020 and permanent repairs to the system continue.

As of December 31, 2021, approximately $ 140 million of costs from the windstorm were recorded substantially to “Property, plant and equipment, net” on Alliant Energy’s and IPL’s balance sheets.

In December 2020, IPL received approval from the IUB for utilization of a regulatory account to track certain incremental costs and benefits incurred resulting from the windstorm.

These incremental costs and benefits were not addressed in the IUB’s order for IPL’s 2020 forward-looking Test Period electric subsequent proceeding, and are expected to be addressed in future regulatory proceedings.

Tax benefits and the incremental operation and maintenance expenses resulting from the windstorm were deferred and recorded as a net regulatory liability of $ 8 million as of December 31, 2021, which is included in “Other” regulatory liabilities in the above table.

Rate Reviews -

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In addition, as discussed in Note 1(g) , the net impact of certain costs and benefits resulting from IPL’s 1,000 MW expansion of wind generation in 2019 and 2020 is being recovered from its retail electric customers through the renewable energy rider.

The agreement also includes IPL providing retail electric billing credits, which began in the third quarter of 2020 and will continue through June 2021, and in aggregate include $ 27 million of excess deferred tax benefits and $ 8 million from a partial refund of interim rates implemented in 2019.

The agreement also includes IPL providing retail electric billing credits, which began in the third quarter of 2020 through June 2021, and in aggregate include $ 27 million of excess deferred tax benefits and $ 8 million from a partial refund of interim rates implemented in 2019.

In 2021, the IUB issued an order for IPL’s 2020 forward-looking Test Period electric subsequent proceeding, which compared actual revenues and costs to those initially forecasted by IPL, and authorized IPL to maintain its current retail electric rates.

IPL’s Retail Gas Rate Review (2020 Forward-looking Test Period) - In March 2019, IPL filed a request with the IUB to increase annual gas base rates for its Iowa retail gas customers based on a 2020 forward-looking Test Period.

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In December 2019, the IUB issued an order approving the settlement with final rates, which were effective January 10, 2020.

IPL’s Retail Electric Rate Review (2016 Test Year) - In April 2017, IPL filed a request with the IUB to increase annual electric base rates for its Iowa retail electric customers based on a 2016 historical Test Year.

An interim retail electric base rate increase of $ 102 million, on an annual basis, was implemented effective April 13, 2017.

In September 2017, IPL reached a partial, non-unanimous settlement agreement with intervenor groups for an annual retail electric base rate increase of $ 130 million.

In February 2018, the IUB issued an order approving the settlement with final rates effective May 1, 2018.

In 2021, the IUB issued an order for IPL’s 2020 forward-looking Test Period gas subsequent proceeding, which compared actual revenues and costs to those initially forecasted by IPL, and authorized IPL to maintain its current retail gas rates.

WPL’s Retail Electric and Gas Rate Review (2019/2020 Forward-looking Test Period) - In December 2018, the PSCW issued an order approving WPL’s proposed settlement for its retail electric and gas rate review covering the 2019/2020 Test Period, which was based on a stipulated agreement between WPL and intervenor groups.

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In addition, WPL’s amortization of excess deferred taxes resulting from the remeasurement of accumulated deferred income taxes caused by Federal Tax Reform was used to offset increases in WPL’s 2020 increased revenue requirements.

WPL’s Retail Electric and Gas Rate Review (2021 Forward-looking Test Period) - In December 2020, the PSCW issued an order authorizing WPL to maintain its then current retail electric and gas base rates, authorized return on common equity, regulatory capital structure and earnings sharing mechanism through the end of 2021.

WPL utilized anticipated fuel-related cost savings and excess deferred income tax benefits in 2021 to offset the revenue requirement impacts of increasing electric and gas rate base, including the Kossuth wind farm, which was placed in service in October 2020, and the expansion of its gas distribution system in Western Wisconsin, which was placed in service in November 2020.

WPL’s Retail Fuel-related Rate Filing (2020 Forward-looking Test Period) - In December 2019, WPL received an order from the PSCW authorizing an annual retail electric rate decrease of $ 29 million, or approximately 2 %, effective January 1, 2020.

The decrease primarily reflected a change in expected fuel-related costs in 2020.

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PROPERTY, PLANT AND EQUIPMENT

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Leased Sheboygan Falls Energy Facility, net (b) — — — — 21 27

Leased land for solar generation, net 11 — — — 11 —

Construction work in progress 778 405 174 185 604 220

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Total property, plant and equipment $ 14,987 $ 14,336 $ 7,983 $ 7,889 $ 6,538 $ 6,022

(a) In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring these EGUs by the end of 2022.

Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5, met the criteria to be considered probable of abandonment as of December 31, 2020.

IPL and WPL are currently allowed a full recovery of and a full return on its respective EGU from both its retail and wholesale customers.

(a) In 2020, IPL and WPL received approval from MISO to retire Lansing and Edgewater Unit 5, respectively, and currently anticipate retiring Lansing by the end of 2022 and Edgewater Unit 5 by early 2023.

In 2021, WPL received approval from MISO to retire Columbia Units 1 and 2, and currently anticipates retiring Columbia Unit 1 by the end of 2023 and Columbia Unit 2 by the end of 2024.

Alliant Energy and IPL concluded that Lansing, and Alliant Energy and WPL concluded that Edgewater Unit 5 and Columbia Units 1 and 2, met the criteria to be considered probable of abandonment as of December 31, 2021.

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 disallowance was required as of December 31, 2021.

As of December 31, 2021, net book values were $ 245 million for Lansing, $ 527 million for Edgewater Unit 5, and $ 460 million for Columbia Units 1 and 2 in aggregate.

(b) Less accumulated amortization of $ 100 million and $ 95 million for WPL as of December 31, 2021 and 2020, respectively.

The leased Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $ 67 million and $ 63 million for Alliant Energy as of December 31, 2021 and 2020, respectively.

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Non-utility and Other - The non-utility and other property, plant and equipment recorded on Alliant Energy’s balance sheets include the following:

Non-utility Generation - The Sheboygan Falls Energy Facility was placed into service in 2005 and is depreciated using the straight-line method over a 35 -year period.

Non-utility Generation - The Sheboygan Falls Energy Facility was placed in service in 2005 and is depreciated using the straight-line method over a 35 -year period.

Corporate Services and Other - Property, plant and equipment related to Corporate Services include a customer billing and information system for IPL and WPL and other computer software, and the corporate headquarters building located in Madison, Wisconsin.

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The majority of the remaining software is amortized over a 5 -year period.

Other property, plant and equipment include Travero assets (a short-line railway in Iowa and a barge terminal on the Mississippi River).

Other property, plant and equipment include

Travero assets (a short-line rail freight service in Iowa;

a Mississippi River barge, rail and truck freight terminal in Illinois;

freight brokerage services;

and a rail-served warehouse in Iowa, which began operations in 2021).

All Corporate Services and Other property, plant and equipment are depreciated using the straight-line method over periods ranging from 5 to 30 years.

Table of Cont ents

JOINTLY-OWNED ELECTRIC UTILITY PLANT

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Columbia Units 1-2 53.5 % 802 314 6

West Riverside 91.8 % 686 12 13

West Riverside Energy Center and Solar Garden 91.0 % 706 33 3

Forward Wind Energy Center 42.6 % 118 48 —

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NOTE 5 (b) Sales of Accounts Receivable - IPL maintains a Receivables Agreement whereby it may sell its customer accounts receivables, unbilled revenues and certain other accounts receivables to a third party through wholly-owned and consolidated special purpose entities.

The purchase commitment from the third party to which it sells its receivables expires in March 2021.

IPL currently expects to amend and extend the purchase commitment.

In April 2021, IPL amended and extended through March 2023 the purchase commitment from the third party to which it sells its receivables.

IPL pays a monthly fee to the third party that varies based on interest rates, limits on cash proceeds and cash amounts received from the third party.

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Under the Receivables Agreement, IPL has the right to receive cash proceeds, up to a certain limit, from the third party in exchange for the receivables sold.

The limit on cash proceeds fluctuates between $ 90 million and $ 110 million.

Effective April 2021, the limit on cash proceeds is $ 110 million.

Cash proceeds are used by IPL to meet short-term financing needs, and cannot exceed the current limit or amount of receivables available for sale, whichever is less.

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Outstanding aggregate cash proceeds $ 110 $ 96 $ 108 $ 46 $ 9 $ 36

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As of December 31, the attributes of IPL’s receivables sold under the Receivables Agreement were as follows (in millions):

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Unbilled utility revenues 104 92

Other receivables — 1

Receivables sold to third party 229 206

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ATC Holdings 16 %, 20 %

$ 338 $ 331 ($ 43 ) ($ 47 ) ($ 45 )

Non-utility wind farm in Oklahoma 50 % 99 103 ( 4 ) ( 8 ) ( 5 )

Corporate venture investments Various 52 31 ( 13 ) ( 4 ) ( 1 )

Other Various 19 11 ( 2 ) ( 2 ) ( 2 )

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Non-utility Wind Farm in Oklahoma - The non-utility wind farm located in Oklahoma provides electricity to a third-party under a long-term PPA, and has both cash and tax equity ownership.

The equity income recognized in 2018 was primarily related to the impacts of Federal Tax Reform.

The liquidation method utilized to recognize Alliant Energy’s share of the wind farm’s earnings includes utilizing the federal income tax rate in effect as of the end of the measurement period.

The lower federal income tax rate effective as of January 1, 2018 resulted in an acceleration of earnings attributable to Alliant Energy’s interest in the Oklahoma wind farm.

This increase in earnings is expected to reverse over time.

Alliant Energy does not maintain or operate the wind farm, and provided a parent guarantee of its subsidiary’s indemnification obligations under the operating agreement and PPA.

Refer to Note 17(d) for discussion of the guarantee.

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Corporate Venture Investments - Alliant Energy has various minority ownership interests in regional and national venture funds, including a coalition with different energy companies across the U.S., working together to help identify and research innovative products, technologies and business models within the emerging energy economy.

COMMON EQUITY

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Equity forward agreements — 4,275,127 8,358,973

At-the-market offering programs — — 4,171,013

Shareowner Direct Plan 492,565 472,283 501,808

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Alliant Energy used the net proceeds from the settlements for general corporate purposes.

At-the-Market Offering Program - In 2018, Alliant Energy filed a prospectus supplement under which it could sell up to $ 175 million of its common stock through an at-the-market offering program.

In 2018, Alliant Energy issued 4,171,013 shares of common stock through this program and received cash proceeds of $ 173 million, net of $ 2 million in commissions and fees.

The 2018 at-the-market offering program has expired.

Shareowner Direct Plan - Alliant Energy satisfies its requirements under the Shareowner Direct Plan (dividend reinvestment and stock purchase plan) by acquiring Alliant Energy common stock through original issue, rather than on the open market.

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IPL is authorized to issue up to 16,000,000 shares of cumulative preferred stock in aggregate.

Information related to the carrying value of IPL’s cumulative preferred stock at December 31 was as follows:

Series Liquidation Preference/Stated Value Shares Authorized Shares Outstanding 2020 2019

(in millions)

Information related to IPL’s cumulative preferred stock at December 31, 2020 was as follows (dollars in millions):

Series Liquidation Preference/Stated Value Shares Authorized Shares Outstanding Carrying Value

5.1 % $ 25 8,000,000 8,000,000 $ 200

IPL may, at its option, redeem the 5.1 % cumulative preferred stock for cash at a redemption price of $ 25 per share plus accrued and unpaid dividends up to the redemption date.

The current articles of incorporation of IPL contain a provision that grants the holders of its cumulative preferred stock voting rights to elect two members of IPL’s Board of Directors if preferred dividends equal to six or more quarterly dividend requirements (whether or not consecutive) are in arrears.

Such voting rights would not provide the holders of IPL’s preferred stock control of the Board of Directors and could not force IPL to redeem its preferred stock.

In December 2021, IPL redeemed all 8,000,000 outstanding shares of its 5.1 % cumulative preferred stock at the $ 25 per share par value for $ 200 million plus accrued and unpaid dividends up to the redemption date.

In 2021, Alliant Energy and IPL recorded a $ 5 million non-cash charge related to this transaction in “Preferred dividend requirements” in their income statements.

NOTE 9 (a) Short-term Debt - Alliant Energy and its subsidiaries maintain committed bank lines of credit to provide short-term borrowing flexibility and back-stop liquidity for commercial paper outstanding.

At December 31, 2020, the short-term borrowing capacity under a single credit facility agreement, which expires in August 2023, totaled $ 1 billion ($ 450 million for Alliant Energy at the parent company level, $ 250 million for IPL and $ 300 million for WPL).

At December 31, 2021, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2026, totaled $ 1 billion ($ 450 million for Alliant Energy at the parent company level, $ 250 million for IPL and $ 300 million for WPL).

Subject to certain conditions, Alliant Energy (at the parent company level), IPL and WPL may each reallocate and change its sublimit up to $ 500 million, $ 400 million and $ 500 million, respectively, within the $ 1 billion total commitment.

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Available credit facility capacity $ 485 $ 611 $ 250 $ 250 $ 64 $ 43

Table of Cont ents

Alliant Energy IPL WPL

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3.25 %, due 2024

$ 500 $ 500 $— $ 500 $ 500 $—

3.4 %, due 2025

250 250 — 250 250 —

5.5 %, due 2025

50 50 — 50 50 —

4.1 %, due 2028

500 500 — 500 500 —

3.6 %, due 2029

2.3%, due 2030 (b) 400 400 — — — —

300 300 — 300 300 —

2.3 %, due 2030

400 400 — 400 400 —

6.45 %, due 2033

100 100 — 100 100 —

6.3 %, due 2034

125 125 — 125 125 —

6.25 %, due 2039

300 300 — 300 300 —

4.7 %, due 2043

250 250 — 250 250 —

3.7 %, due 2046

3.65% (Retired in 2020) — — — 200 200 —

300 300 — 300 300 —

3.5 %, due 2049

300 300 — 300 300 —

3.1 %, due 2051 (b)

300 300 — — — —

3,675 3,675 — 3,375 3,375 —

Debentures (a):

2.25 %, due 2022

250 — 250 250 — 250

3.05 %, due 2027

300 — 300 300 — 300

3 %, due 2029

350 — 350 350 — 350

1.95 %, due 2031 (c)

300 — 300 — — —

6.25 %, due 2034

100 — 100 100 — 100

6.375 %, due 2037

300 — 300 300 — 300

7.6 %, due 2038

250 — 250 250 — 250

4.1 %, due 2044

3.65%, due 2050 (c) 350 — 350 — — —

4.6% (Retired in 2020) — — — 150 — 150

250 — 250 250 — 250

AEF term loan credit agreement through March 2022, 1% at December 31, 2020 (with Alliant Energy as guarantor) (d) 300 — — — — —

3.65 %, due 2050

350 — 350 350 — 350

2,450 — 2,450 2,150 — 2,150

AEF term loan credit agreement through March 2022, 1 % at December 31, 2021 (with Alliant Energy as guarantor)

300 — — 300 — —

Corporate Services 3.45 % senior notes, due 2022 (a)

75 — — 75 — —

AEF 3.75 % senior notes, due 2023 (with Alliant Energy as guarantor) (a)

AEF 1.4% senior notes, due 2026 (with Alliant Energy as guarantor) (a)(e) 200 — — — — —

400 — — 400 — —

AEF 1.4 % senior notes, due 2026 (with Alliant Energy as guarantor) (a)

200 — — 200 — —

AEF 4.25 % senior notes, due 2028 (with Alliant Energy as guarantor) (a)

300 — — 300 — —

Sheboygan Power, LLC 5.06 % senior secured notes, due 2022 to 2024 (secured by the Sheboygan Falls Energy Facility and related assets) (a)

AEF term loan credit agreement, 2% at December 31, 2019 (with Alliant Energy as guarantor) (Retired in 2020) — — — 300 — —

24 — — 31 — —

Other, 1 % at December 31, 2021, due 2022 to 2025

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Unamortized debt (discount) and premium, net ( 15 ) ( 9 ) ( 6 ) ( 15 ) ( 8 ) ( 6 )

Long-term debt, net (f) $ 6,769 $ 3,345 $ 2,130 $ 5,533 $ 2,947 $ 1,783

Long-term debt, net (d) $ 6,735 $ 3,643 $ 2,179 $ 6,769 $ 3,345 $ 2,130

(a) Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer.

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Treasury rates at the time of redemption.

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(b) In June 2020, IPL issued $ 400 million of 2.3% senior debentures due 2030.

The net proceeds from the issuance were used by IPL to retire its $ 200 million 3.65% senior debentures that would have matured in September 2020 and for general corporate purposes.

The net proceeds from the issuance were used by WPL to reduce borrowings under the single credit facility and for general corporate purposes.

(d) In March 2020, 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 would have expired in April 2020.

(e) In November 2020, AEF issued $ 200 million of 1.4% senior notes due 2026.

The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes.

(f) There were no significant sinking fund requirements related to the outstanding long-term debt.

(b) In November 2021, IPL issued $ 300 million of 3.1 % senior debentures due 2051.

The net proceeds from the issuance were used by IPL to retire its cumulative preferred stock in 2021 and for general corporate purposes.

The debentures were issued as green bonds, and an amount in excess of the net proceeds was disbursed for the construction and development of WPL’s wind and solar EGUs.

(d) There were no significant sinking fund requirements related to the outstanding long-term debt.

Five-Year Schedule of Long-term Debt Maturities - At December 31, 2021, long-term debt maturities for 2022 through 2026 were as follows (in millions):

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Operating Leases - Alliant Energy’s, IPL’s and WPL’s operating leases primarily include leases of space on telecommunication towers and leases of property.

At December 31, operating lease details are as follows (dollars in millions):

Operating lease details are as follows (dollars in millions):

December 31, 2021 December 31, 2020

Alliant Energy IPL WPL Alliant Energy IPL WPL

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Weighted average discount rate 4 % 4 % 4 % 4 % 4 % 4 %

Finance Lease - WPL is currently leasing the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business through 2025, the initial lease term.

Finance Leases - WPL is currently leasing the Sheboygan Falls Energy Facility from AEF’s Non-utility Generation business through 2025, the initial lease term.

WPL is responsible for the operation of the EGU and has exclusive rights to its output.

This finance lease contains two lease renewal periods, which are not included in the finance lease obligation, as well as an option to purchase the facility at the end of the initial lease term.

WPL’s finance lease details are as follows (dollars in millions):

December 31, 2020 December 31, 2019

For Alliant Energy, the leased Sheboygan Falls Energy Facility is eliminated upon consolidation and is therefore is not reflected in Alliant Energy’s amounts below.

Related to its investments in solar generation, WPL entered into land lease agreements with unaffiliated parties that commenced in 2021.

The leases have various terms with optional renewal periods that are assumed to be extended through the end of the estimated useful lives of the solar generating facilities.

The leases do not contain purchase options and are fixed lease payments.

Finance lease details are as follows (dollars in millions):

Alliant Energy WPL

December 31, 2021 December 31, 2021 December 31, 2020

Property, plant and equipment, net:

Sheboygan Falls Energy Facility n/a $ 21 $ 27

Leased land for solar generation $ 11 11 —

$ 11 $ 32 $ 27

Other current liabilities:

Finance lease obligations - Sheboygan Falls Energy Facility 42 51

Sheboygan Falls Energy Facility n/a $ 10 $ 9

Leased land for solar generation $ 1 1 —

Other liabilities:

Sheboygan Falls Energy Facility n/a 31 42

Leased land for solar generation 11 11 —

Total finance lease liabilities $ 12 $ 53 $ 51

Remaining lease term 4 years 5 years

Discount rate 11 % 11 %

Depreciation expense $ 6 $ 6

Weighted average remaining lease term 34 years 10 years 4 years

Weighted average discount rate 3 % 9 % 11 %

2021 2021 2020 2019

Depreciation and amortization expenses $ — $ 6 $ 6 $ 6

Interest expense — 5 6 7

Total finance lease expense $ — $ 11 $ 12 $ 13

Table of Cont ents

Expected Maturities - As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

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WPL 1 1 1 1 1 1 6 1 5

WPL’s Finance Lease:

Sheboygan Falls Energy Facility 15 15 15 15 5 — 65 14 51

Finance Leases:

Alliant Energy — — — — 1 19 20 8 12

WPL 15 15 15 6 1 19 71 18 53

Revenues from Alliant Energy’s, IPL’s and WPL’s utility businesses are primarily from electric and gas sales provided to customers based on approved tariffs or specific contracts with customers.

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Revenues from Alliant Energy’s non-utility business customers are primarily from its Travero business, which includes a short-line rail freight service in Iowa;

a barge, rail and truck freight terminal on the Mississippi River;

and freight brokerage and logistics management services.

Table of Cont ents

a Mississippi River barge, rail and truck freight terminal in Illinois;

freight brokerage services;

and a rail-served warehouse in Iowa, which began operations in 2021.

Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):

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($ 74 ) ($ 57 ) $ 69 ($ 36 ) ($ 47 ) $ 24 ($ 51 ) ($ 19 ) $ 49

Table of Cont ents

Income Tax Rates - The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

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State income taxes, net of federal benefits 2 2 7 ( 1 ) ( 1 ) 8 6 6 6

Production tax credits ( 17 ) ( 9 ) ( 5 ) ( 28 ) ( 13 ) ( 5 ) ( 7 ) ( 5 ) ( 7 )

Amortization of excess deferred taxes (Refer to Note 2 )

( 18 ) ( 13 ) ( 1 ) ( 4 ) ( 5 ) — ( 43 ) ( 26 ) ( 2 )

Production tax credits ( 17 ) ( 17 ) ( 9 ) ( 27 ) ( 28 ) ( 13 ) ( 6 ) ( 7 ) ( 5 )

Effect of rate-making on property-related differences ( 1 ) ( 3 ) ( 6 ) ( 2 ) ( 4 ) ( 10 ) ( 1 ) ( 2 ) ( 3 )

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IPL’s tax benefit riders — — ( 1 ) — — ( 1 ) — — —

Federal Tax Reform adjustments — — ( 1 ) — — — — — ( 2 )

Other items, net — ( 1 ) ( 1 ) — — — ( 1 ) — —

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Valuation Allowances - Alliant Energy currently expects its federal net operating losses carryforwards will not be fully utilized until 2023.

Because taxable income must be reduced by federal net operating losses carryforwards prior to utilizing federal tax credit carryforwards, Alliant Energy currently does not expect to utilize 2002 vintage federal credit carryforwards prior to their expiration in 2022, resulting in valuation allowances that remain as of December 31, 2020.

Alliant Energy currently expects to be able to utilize 2003 vintage federal credit carryforwards prior to their expiration in 2023, and as a result, in 2020, Alliant Energy reversed $ 4 million of previously recorded valuation allowances related to these federal credit carryforwards.

Uncertain Tax Positions - At December 31, 2021, 2020 and 2019, there were no uncertain tax positions or penalties accrued related to uncertain tax positions.

As of December 31, 2021, no material changes to unrecognized tax benefits are expected during the next 12 months.

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Open tax years - Tax years that remain subject to the statute of limitations in the major jurisdictions for each of Alliant Energy, IPL and WPL are as follows:

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(a) The 2017 federal tax return is effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return.

(a) The 2018 and 2019 federal tax returns are effectively settled as a result of participation in the IRS Compliance Assurance Program, which allows Alliant Energy and the IRS to work together to resolve issues related to Alliant Energy’s current tax year before filing its federal income tax return.

The statute of limitations for these federal tax returns expires three years from each filing date.

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Federal Tax Reform Adjustments - In 2018, additional rules were issued related to Federal Tax Reform, including clarifications of the treatment of bonus depreciation deductions, which impacted the federal income tax return for the calendar year 2017.

As a result of these clarifying rules, Alliant Energy, IPL and WPL recorded tax benefits of $ 6 million, $ 1 million and $ 5 million, respectively, in 2018.

Iowa Tax Reform - In 2018, Iowa tax reform was enacted, resulting in a reduction in the Iowa income tax rate from 12 % to 9.8 %, effective January 1, 2021, and the elimination of the deduction for federal income taxes, effective January 1, 2022, for taxes related to 2020 and prior.

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Rate of compensation increase 3.30 % 3.65 % 3.65 % N/A N/A N/A

Table of Cont ents

Expected rate of return on plan assets - The expected rate of return on plan assets is based on projected asset class returns using target allocations.

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(d) Settlement losses related to payments made to retired executives of Alliant Energy and lump sum payments related to IPL’s qualified defined benefit pension plan.

Table of Cont ents

Benefit Plan Assets and Obligations - A reconciliation of the funded status of qualified and non-qualified defined benefit pension and OPEB plans to the amounts recognized on the balance sheets at December 31 was as follows (in millions):

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Plan participants’ contributions — — 5 4

Actuarial loss 132 124 18 14

Actuarial (gain) loss ( 46 ) 132 ( 12 ) 18

Gross benefits paid ( 99 ) ( 115 ) ( 19 ) ( 19 )

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Plan participants’ contributions — — 2 1

Actuarial loss 60 56 8 6

Actuarial (gain) loss ( 23 ) 60 ( 4 ) 8

Gross benefits paid ( 48 ) ( 53 ) ( 8 ) ( 8 )

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Under funded status at December 31 ($ 105 ) ($ 162 ) ($ 10 ) ($ 17 )

Table of Cont ents

Defined Benefit Pension Plans OPEB Plans

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Plan participants’ contributions — — 2 2

Actuarial loss 55 54 5 5

Actuarial (gain) loss ( 18 ) 55 ( 5 ) 5

Gross benefits paid ( 43 ) ( 40 ) ( 8 ) ( 8 )

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$ 187 $ 232 $ 17 $ 24

Actuarial gains related to benefit obligations in 2021 for defined benefit pension and OPEB plans were primarily due to increases in the discount rates.

Actuarial losses related to benefit obligations in 2020 for defined benefit pension and OPEB plans were primarily due to decreases in the discount rates, partially offset by the impact of updated mortality projection tables.

Actuarial losses related to benefit obligations in 2019 for defined benefit pension and OPEB plans were primarily due to decreases in the discount rates and experience losses, partially offset by the impact of the updated base mortality table.

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Accumulated benefit obligations, aggregate amounts applicable to defined benefit pension and OPEB plans with accumulated benefit obligations in excess of plan assets, as well as defined benefit pension plans with projected benefit obligations in excess of plan assets as of the December 31 measurement date are as follows (in millions):

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$ 103 $ 100 $ 99 $ 99 $ 99 $ 458

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IPL 2022 2023 2024 2025 2026 2027 - 2031

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Investment risk of plan assets is mitigated through diversification, including U.S.

and international equity, fixed income, global asset and risk parity strategies.

Global asset and risk parity strategies may include investments in global equity, global debt, commodities and currencies.

and international equity, fixed income and global asset strategies.

Global asset strategies may include investments in global equity, global debt and currencies.

Defined Benefit Pension Plan Assets - The asset mix of defined benefit pension plans is governed by allocation targets.

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Global asset securities 5 % - 15 % 9 %

Risk parity securities 5 % - 15 % 9 %

Fixed income securities 25 % - 45 % 33 %

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0 % - 55 % 35 %

Equity securities - international 0 % - 34 % 1 %

Fixed income securities 40 % - 100 % 64 %

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These fair value amounts are included below to reconcile the fair value hierarchy to the respective total plan assets.

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At December 31, the fair values of qualified and non-qualified defined benefit pension plan assets were as follows (in millions):

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Equity securities - international — — — — 3 3 — —

Global asset securities 1 1 — — — — — —

Fixed income securities 60 58 2 — 72 71 1 —

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Total OPEB plan assets $ 106 $ 108

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Fair Level Level Level Fair Level Level Level

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Cash and equivalents $ 1 $ — $ 1 $ — $ 1 $ — $ 1 $ —

Equity securities - U.S.

8 8 — — — — — —

Fixed income securities 42 42 — — 51 51 — —

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WPL Value 1 2 3 Value 1 2 3

Cash and equivalents $ 1 $ — $ 1 $ — $ — $ — $ — $ —

Equity securities - U.S.

1 1 — — — — — —

Fixed income securities 15 15 — — 18 18 — —

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Alliant Energy satisfies share payouts related to equity awards through the issuance of new shares of its common stock.

Alliant Energy also has the DLIP, which permits the grant of cash-based long-term awards, including performance units, restricted cash awards and restricted units, to certain key employees.

At December 31, 2020, performance units and restricted units (performance- and time-vesting) were outstanding under the DLIP, and the amount of nonvested restricted units was not material.

There is no limit to the number of grants that can be made under the DLIP and Alliant Energy satisfies all payouts under the DLIP through cash payments.

Alliant Energy also granted cash-based long-term awards, including performance units, restricted cash awards and restricted units, to certain key employees, under the DLIP.

At December 31, 2021, no awards were outstanding under the DLIP.

Nonvested awards generally do not have non-forfeitable rights to dividends or dividend equivalents when dividends are paid to common shareowners.

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Performance shares granted in 2021, 2020 and 2019 are to be paid out in shares of Alliant Energy common stock and are accounted for as equity awards.

The fair value of each performance share granted in 2020 and 2019 is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a three-year performance period.

The actual number of 2020 and 2019 performance shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200 % of the target number of shares.

If minimum performance targets are not met during the performance period, these performance

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shares are forfeited.

The fair value of each of these performance shares is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market condition contained in the agreement during a three-year performance period.

The actual number of these performance shares that will be paid out upon vesting is dependent upon actual performance and may range from zero to 200 % of the target number of shares.

If minimum performance targets are not met during the performance period, these performance shares are forfeited.

Compensation expense is recorded ratably over the performance period based on the fair value of the awards at the grant date.

A summary of the 2021, 2020 and 2019 performance shares activity, with amounts representing the target number of awards, was as follows:

Performance Shares - Equity Weighted Average

Grant Date Fair Value Performance Shares - Equity Weighted Average

Grant Date Fair Value

2021 2020 2019

Performance Shares - Equity Weighted Average Grant Date Fair Value Performance Shares - Equity Weighted Average Grant Date Fair Value Performance Shares - Equity Weighted Average Grant Date Fair Value

Nonvested awards, January 1 129,156 $ 54.63 74,193 $ 47.44 — $ —

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Nonvested awards, December 31 196,429 51.59 129,156 54.63 74,193 47.44

Performance Shares and Performance Units - Liability Awards - Payouts of performance shares granted prior to 2019 under the Amended and Restated 2010 OIP and performance units under the DLIP to key employees are contingent upon achievement over three-year periods of specified performance criteria, which currently is total shareowner return relative to an investor-owned utility peer group.

Performance shares granted prior to 2019 can be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock.

Performance units must be paid out in cash.

Alliant Energy assumes it will make future payouts of its performance shares granted prior to 2019 and performance units in cash;

therefore, these performance shares and performance units are accounted for as liability awards.

Compensation expense for these performance shares and performance units is recorded ratably over the performance period based on the fair value of the awards at each reporting period.

Performance Shares and Performance Units - Liability Awards - Payouts of performance shares granted prior to 2019 under the Amended and Restated 2010 OIP and performance units granted prior to 2019 under the DLIP to key employees were contingent upon achievement over three-year periods of specified performance criteria, which was total shareowner return relative to an investor-owned utility peer group.

Performance shares granted prior to 2019 were able to be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock.

Performance units granted prior to 2019 were paid out in cash.

Alliant Energy assumed it would make future payouts of its performance shares granted prior to 2019 and performance units in cash;

therefore, these performance shares and performance units were accounted for as liability awards.

The fair value of each performance share and performance unit accounted for as a liability award was based on the closing market price of one share of Alliant Energy common stock at the end of the performance period.

The actual payout for performance shares and performance units was dependent upon actual performance and may range from zero to 200 % of the

target number of awards.

Compensation expense for these performance shares and performance units was recorded ratably over the performance period based on the fair value of the awards at each reporting period.

A summary of these performance shares and performance units activity, with amounts representing the target number of awards, was as follows:

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Nonvested awards, January 1 68,307 131,872 203,188 16,801 34,574 57,761

Granted — — 74,163 — — 19,840

Vested ( 68,307 ) ( 63,565 ) ( 66,322 ) ( 16,801 ) ( 16,661 ) ( 20,131 )

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Nonvested awards, December 31 — 68,307 131,872 — 16,801 34,574

Fair Value of Awards - The fair value of each performance share and performance unit accounted for as a liability award is based on the closing market price of one share of Alliant Energy common stock at the end of the performance period.

The actual payout for performance shares and performance units is dependent upon actual performance and may range from zero to 200 % of the target number of awards.

At December 31, 2020, the Alliant Energy common stock closing price was $ 51.53 , and additional information related to the fair value of nonvested performance shares and performance units granted in 2018 was as follows:

Performance Shares Performance Units

Nonvested awards at target 68,307 16,801

Estimated payout percentage based on performance criteria 172.5 % 172.5 %

Fair values of each nonvested award $ 88.89 $ 88.89

Vested Awards - Certain performance shares and performance units vested, resulting in payouts (a combination of cash and common stock for the performance shares and cash only for the performance units) as follows:

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Restricted stock units granted in 2021, 2020 and 2019 are to be paid out in shares of Alliant Energy common stock and are accounted for as equity awards.

The fair value of each restricted stock unit granted in 2020 and 2019 is based on the closing market price of one share of Alliant Energy common stock on the grant date of the award.

The fair value of each of these restricted stock units is based on the closing market price of one share of Alliant Energy common stock on the grant date of the award.

Compensation expense is recorded ratably over the performance period based on the fair value of the awards on the grant date.

A summary of the 2021, 2020 and 2019 restricted stock units activity was as follows:

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Restricted Stock Units - Equity Weighted Average

Grant Date Fair Value Restricted Stock Units - Equity Weighted Average

Grant Date Fair Value

2021 2020 2019

Restricted Stock Units - Equity Weighted Average Grant Date Fair Value Restricted Stock Units - Equity Weighted Average Grant Date Fair Value Restricted Stock Units - Equity Weighted Average Grant Date Fair Value

Nonvested units, January 1 146,549 $ 51.54 89,281 $ 46.04 — $ —

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Nonvested units, December 31 217,819 50.54 146,549 51.54 89,281 46.04

Restricted Stock Units - Liability Awards - Payouts of restricted stock units granted prior to 2019 are based on the expiration of a three-year time-vesting period and can be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock.

Alliant Energy assumes it will make future payouts of its restricted stock units granted prior to 2019 in cash;

therefore, restricted stock units granted prior to 2019 are accounted for as liability awards.

The fair value of each restricted stock unit granted prior to 2019 is based on the closing market price of one share of Alliant Energy common stock at the end of the time-vesting period.

Compensation expense is recorded ratably over the performance period based on the fair value of the awards at each reporting period.

Restricted Stock Units - Liability Awards - Payouts of restricted stock units granted prior to 2019 were based on the expiration of a three-year time-vesting period and were able to be paid out in shares of Alliant Energy common stock, cash or a combination of cash and stock.

Alliant Energy assumed it would make future payouts of its restricted stock units granted prior to 2019 in cash;

therefore, restricted stock units granted prior to 2019 were accounted for as liability awards.

The fair value of each restricted stock unit granted prior to 2019 was based on the closing market price of one share of Alliant Energy common stock at the end of the time-vesting period.

Compensation expense was recorded ratably over the performance period based on the fair value of the awards at each reporting period.

A summary of the restricted stock units granted prior to 2019 activity was as follows:

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Nonvested units, January 1 58,550 113,033 174,163

Granted — — 63,568

Vested ( 58,550 ) ( 54,483 ) ( 56,849 )

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If minimum performance targets are not met during the performance period, these units are forfeited.

Performance restricted stock units generally must be paid out in shares and are accounted for as equity awards.

Performance restricted stock units are to be paid out in shares and are accounted for as equity awards.

The fair value of each performance restricted stock unit is based on the closing market price of one share of Alliant Energy common stock on the grant date of the award.

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Fair market value 24 20

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Interest, Equity and Mutual Fund Accounts - Distributions from participants’ interest, equity and mutual fund accounts are in the form of cash payments.

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ASSET RETIREMENT OBLIGATIONS

Recognized AROs relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind farms, ash ponds, active ash landfills, above ground storage tanks, coal yards and solar generation.

Recognized AROs relate to legal obligations for the removal, closure or dismantlement of several assets including, but not limited to, wind farms, ash ponds, active ash landfills, coal yards, above ground storage tanks and solar generation.

Recognized AROs also include legal obligations for the management and final disposition of asbestos and polychlorinated biphenyls.

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Liabilities settled ( 17 ) ( 13 ) ( 13 ) ( 9 ) ( 4 ) ( 4 )

Liabilities incurred (a) 48 26 38 26 10 —

Liabilities incurred 3 48 — 38 3 10

Accretion expense 7 7 5 5 2 2

Balance, December 31 $ 294 $ 251 $ 213 $ 177 $ 81 $ 74

(a) In 2020, IPL placed in service the Whispering Willow North, Golden Plains and Richland wind sites, and WPL placed in service the Kossuth wind site.

As a result, Alliant Energy, IPL and WPL recognized additional AROs in 2020, which resulted in corresponding increases in property, plant and equipment, net on the respective balance sheets.

DERIVATIVE INSTRUMENTS

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WPL 6,488 2022 91,110 2022-2030 1,923 2022-2023 3,024 2022

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Financial Statement Presentation - Derivative instruments are recorded at fair value each reporting date on the balance sheet as assets or liabilities.

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Non-current derivative liabilities 1 16 — 9 1 7

In 2021, Alliant Energy’s, IPL’s and WPL’s derivative assets increased and derivative liabilities decreased primarily as a result of higher natural gas prices.

Based on IPL’s and WPL’s natural gas cost recovery mechanisms, this resulted in corresponding decreases in derivative regulatory assets and increases in derivative regulatory liabilities on the balance sheets.

Credit Risk-related Contingent Features - Various agreements contain credit risk-related contingent features, including requirements to maintain certain credit ratings and/or limitations on liability positions under the agreements based on credit ratings.

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Refer to Note 5(b) for additional information regarding deferred proceeds.

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Long-term debt (including current maturities) - The fair value of long-term debt instruments was based on a discounted cash flow methodology using observable data from comparably traded securities with similar credit profiles, and was substantially classified as Level 2.

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Derivatives 4 — 3 1 4 12 — 12 — 12

Long-term debt (incl.

current maturities) 3,345 — 4,021 — 4,021 3,147 — 3,489 — 3,489

Long-term debt 3,643 — 4,124 — 4,124 3,345 — 4,021 — 4,021

WPL 2021 2020

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current maturities) 2,429 — 2,862 — 2,862 2,130 — 2,690 — 2,690

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Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

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Total net gains included in changes in net assets (realized/unrealized) 6 11 — —

Transfers out of Level 3 (a) — 4 — —

Purchases 21 14 — —

Sales ( 1 ) ( 1 ) — —

Settlements (b) ( 16 ) ( 17 ) — 69

Settlements (a) ( 26 ) ( 16 ) 26 —

Ending balance, December 31 $ 29 $ 29 $ 214 $ 188

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Beginning balance, January 1 $ 26 $ 18 $ 188 $ 188

Total net gains included in changes in net assets (realized/unrealized) 10 11 — —

Transfers out of Level 3 (a) — 2 — —

Total net gains (losses) included in changes in net assets (realized/unrealized) ( 3 ) 10 — —

Purchases 16 11 — —

Sales ( 1 ) ( 1 ) — —

Settlements (b) ( 12 ) ( 13 ) — 69

Settlements (a) ( 20 ) ( 12 ) 26 —

Ending balance, December 31 $ 18 $ 26 $ 214 $ 188

The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at December 31 ($ 3 ) $ 10 $ — $ —

WPL Commodity Contract Derivative

Assets and (Liabilities), net

Beginning balance, January 1 $ 3 $ 3

Total net gains included in changes in net assets (realized/unrealized) 9 1

Purchases 5 3

Settlements ( 6 ) ( 4 )

Ending balance, December 31 $ 11 $ 3

The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at December 31 $ 9 $ 1

(a) Observable market inputs became available for certain commodity contracts previously classified as Level 3 for transfers out of Level 3.

(b) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

(a) Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Commodity Contracts - The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets at December 31 as follows (in millions):

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$ 452 $ 256 $ 177 $ 110 $ 90 $ 200 $ 1,285

Table of Cont ents

IPL 2022 2023 2024 2025 2026 Thereafter Total

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Alliant Energy is not aware of any material liabilities related to these guarantees that it is probable that it will be obligated to pay;

however, the new credit loss accounting standard adopted on January 1, 2020 requires recognition of a liability for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

With the adoption of this standard, Alliant Energy recorded a pre-tax $ 12 million cumulative effect adjustment to decrease the opening balance of retained earnings as of January 1, 2020.

In April 2020, Whiting Petroleum filed for bankruptcy, and in September 2020, Whiting Petroleum completed its reorganization and emerged from bankruptcy.

As a result of Whiting Petroleum’s completed bankruptcy proceedings, as well as additional information regarding the guarantees obtained from the bankruptcy proceedings, the credit loss liability was decreased to $ 5 million in 2020.

The credit loss liability is recorded in “Other liabilities” on Alliant Energy’s balance sheet as of December 31, 2020.

In 2020, the pre-tax credit loss adjustment of $ 7 million was recorded as a reduction in Alliant Energy’s “Other operation and maintenance” expenses.

however, as of both December 31, 2021 and 2020, a liability of $ 5 million is recorded in “Other liabilities” on Alliant Energy’s balance sheets for expected credit losses related to the contingent obligations that are in the scope of these guarantees.

Non-utility Wind Farm in Oklahoma - In 2017, a wholly-owned subsidiary of AEF acquired a cash equity ownership interest in a non-utility wind farm located in Oklahoma.

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Substantially all of the environmental liabilities recorded on the balance sheets relate to MGP sites.

MGP Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring

Table of Cont ents

Manufactured Gas Plant Sites - IPL and WPL have current or previous ownership interests in various sites that are previously associated with the production of gas for which IPL and WPL have, or may have in the future, liability for investigation, remediation and monitoring costs.

IPL and WPL are working pursuant to the requirements of various federal and state agencies to investigate, mitigate, prevent and remediate, where necessary, the environmental impacts to property, including natural resources, at and around these former MGP sites in order to protect public health and the environment.

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IPL has completed various requirements under the Consent Decree.

IPL’s remaining requirements include fuel switching or retiring Burlington by December 31, 2021 and Prairie Creek Units 1 and 3 by December 31, 2025.

IPL’s remaining requirements include fuel switching or retiring Prairie Creek Units 1 and 3 by December 31, 2025.

Alliant Energy and IPL currently expect to recover material costs incurred by IPL related to compliance with the terms of the Consent Decree from IPL’s electric customers.

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Refer to Notes 5(a) and 15 for details of allowances for expected credit losses and credit risk-related contingent features, respectively.

NOTE 17 (g) MISO Transmission Owner Return on Equity Complaints - A group of MISO cooperative and municipal utilities previously filed complaints with FERC requesting a reduction to the base return on equity used by MISO transmission owners, including ITC and ATC.

The first complaint covered the period from November 12, 2013 through February 11, 2015.

In 2017, IPL and WPL received refunds related to the first complaint period, which were subsequently refunded to their retail and wholesale customers.

The second complaint covered the period from February 12, 2015 through May 11, 2016.

In November 2019, FERC issued an order on the previously filed complaints and reduced the base return on equity used by the MISO transmission owners to 9.88 % effective for the first complaint period and subsequent to September 28, 2016.

The November 2019 FERC order also dismissed the second complaint;

therefore, FERC did not direct refunds to be made for that complaint.

In May 2020, FERC issued an order in response to various rehearing requests and increased the base return on equity used by the MISO transmission owners from 9.88 % to 10.02 % for the first complaint period and subsequent to September 28, 2016, which reduces the refunds originally anticipated to be received by IPL and WPL as a result of FERC’s November 2019 order.

In 2020, IPL and WPL received $ 15 million and $ 5 million, respectively, in refunds related to the FERC orders.

In October 2020, FERC extended the time to complete additional refunds to September 2021.

IPL currently expects that all refunds will be returned to its retail electric customers after refund amounts and timing are known and a refund plan is approved by the IUB.

IPL currently expects that a portion of the refunds will be returned to its retail electric customers in 2021.

Pursuant to PSCW authorization, WPL will retain the refunds to maintain its current retail electric base rates through the end of 2021.

WPL currently expects that any refunds not utilized to maintain base rates would be returned to its customers in WPL’s next retail

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electric rate review proceeding.

Any further changes in FERC’s decisions may have an impact on Alliant Energy’s share of ATC’s future earnings and customer costs.

NOTE 17 (g) Collective Bargaining Agreements - At December 31, 2021, employees covered by collective bargaining agreements represented 54 %, 69 % and 83 % of total employees of Alliant Energy, IPL and WPL, respectively.

In May 2022, WPL’s collective bargaining agreement with International Brotherhood of Electrical Workers Local 965 expires, representing 26 % and 83 % of total employees of Alliant Energy and WPL, respectively.

SEGMENTS OF BUSINESS

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• ATC Holdings, Non-utility, Parent and Other - includes the operations of AEF and its subsidiaries, Corporate Services, the Alliant Energy parent company, and any Alliant Energy parent company consolidating adjustments.

AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, the Sheboygan Falls Energy Facility and other non-utility holdings.

AEF is comprised of Alliant Energy’s interest in ATC Holdings, Travero, a non-utility wind farm, corporate venture investments, the Sheboygan Falls Energy Facility and other non-utility holdings.

Alliant Energy’s administrative support services are directly charged to the applicable segment where practicable.

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Depreciation and amortization 556 49 5 610 5 615

Operating income 679 70 1 750 28 778

Operating income (loss) 643 74 ( 1 ) 716 24 740

Interest expense 243 32 275

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Construction and acquisition expenditures 1,109 182 2 1,293 73 1,366

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ATC Holdings,

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Equity income from unconsolidated investments, net ( 1 ) — — ( 1 ) ( 52 ) ( 53 )

Income taxes 33 15 48

Income tax expense (benefit) 73 ( 4 ) 69

Net income attributable to Alliant Energy common shareowners 517 40 557

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Depreciation and amortization 338 31 6 375

Operating income 358 50 2 410

Operating income (loss) 420 43 ( 3 ) 460

Interest expense 139

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Interest expense 139

Income taxes 24

Income tax benefit ( 47 )

Net income available for common stock 324

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Interest expense 127

Income tax benefit ( 3 )

Income taxes 24

Net income available for common stock 284

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Certain financial information relating to WPL’s business segments, which represent the services provided to its customers, was as follows (in millions):

Table of Cont ents

2021 Electric Gas Other Total

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Interest expense 104

Income taxes 49

Income tax benefit ( 19 )

Net income 249

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As of December 31, 2021 and 2020, WPL owed ATC net amounts of $ 10 million and $ 9 million, respectively.

Table of Cont ents

In 2020, WPL received $ 46 million from ATC related to construction deposits WPL previously provided ATC for transmission network upgrades for West Riverside, which is substantially recorded in “Other” in Alliant Energy’s and WPL’s cash flows from investing activities.

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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 8. Financial Statements and Supplementary Data