10-Q – 2025-11-07 – lnt-20250930.htm

Cost of Gas Sold Expense Variances - The following items contributed to (increased) decreased cost of gas sold expense for the three and nine months ended September 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Nine Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Changes in retail gas volumes and natural gas prices ($6) $1 ($7) ($29) ($6) ($23)
Changes in the regulatory recovery of gas costs 7 — 7 1 2 (1)

$1 $1 $— ($28) ($4) ($24)

Other Operation and Maintenance Expenses Variances - The following items contributed to (increased) decreased other operation and maintenance expenses for the three and nine months ended September 30, 2025 compared to the same periods in 2024 (in millions):

Three Months Nine Months
Alliant Energy IPL WPL Alliant Energy IPL WPL
Higher generation and energy delivery expenses ($13) ($6) ($7) ($11) $— ($11)
Higher incentive compensation expense (5) (3) (2) (10) (5) (5)
Higher energy efficiency expense at IPL (mostly offset by higher revenues) (7) (7) — (7) (7) —
Development costs for new generation (6) (4) (2) (6) (4) (2)

ARO charge in the second quarter of 2024 for steam assets at IPL (Refer to Note 1(d) for details)
— — — 20 20 —
Other 1 8 (1) (6) 2 (4)
($30) ($12) ($12) ($20) $6 ($22)

Other Future Considerations - In addition to items discussed in this report, the following key items could impact Alliant Energy’s, IPL’s and WPL’s future financial condition or results of operations:
• Financing Plans - Alliant Energy currently expects to issue up to $2.4 billion of common stock in aggregate from 2026 through 2029 through the distribution agreement that was executed in May 2025, its Shareholder Direct Plan (up to $25 million in common stock annually) and additional future equity offerings. For the remainder of 2025, WPL currently expects to issue up to $300 million of long-term debt. In 2026, IPL and WPL currently expect to issue up to $500 million and $300 million, respectively, of long-term debt, and AEF and/or Alliant Energy at the parent company level expect to issue up to $300 million of long-term debt in aggregate. AEF and Alliant Energy at the parent company level have $500 million and $575 million, respectively, of long-term debt maturing in 2026.
• Common Stock Dividends - Alliant Energy announced a 5% increase in its targeted 2026 annual common stock dividend to $2.14 per share, which is equivalent to a quarterly rate of $0.535 per share, beginning with the February 2026 dividend payment. The timing and amount of future dividends is subject to approval of quarterly dividend declarations from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.
• Higher Earnings on Increasing Rate Base - Alliant Energy and WPL currently expect increases in electric utility and gas utility revenues in 2026 compared to 2025 due to impacts from increasing revenue requirements related to investments in the utility business (refer to “ Rate Matters ” for further discussion). Additionally, Alliant Energy and IPL currently expect electric utility revenues to increase in 2026 compared to 2025 due to the expiration of tax benefit rider credits in 2025. Furthermore, Alliant Energy, IPL and WPL currently expect a decrease in the effective income tax rate in 2026 compared to 2025 due to additional renewable tax credits from renewable generation and energy storage projects placed in service and/or expected to be placed in service in 2025 and 2026. A majority of the differences between actual renewable tax credits and renewable tax credits used to determine rates are recorded in regulatory assets or regulatory liabilities on the balance sheets until they are reflected in future billings to customers. Investment tax credits resulting from IPL energy storage projects placed in service and/or expected to be placed in service in 2025 and 2026 may be utilized to offset any revenue deficiency on an annual basis up to the earnings sharing mechanism threshold included in IPL’s retail electric rate review settlement agreement.
• Sales Trends - Alliant Energy, IPL and WPL currently expect an increase in retail electric sales in 2026 compared to 2025 driven by expected load growth from new customers who currently expect to build data centers in IPL’s and WPL’s service territories. Refer to “ Growing Customer Demand ” for further discussion.
• Other Operation and Maintenance Expenses - Alliant Energy, IPL and WPL currently expect an increase in other operation and maintenance expenses in 2026 compared to 2025 largely due to higher generation maintenance and energy delivery expenses.
• Depreciation and Amortization Expense - Alliant Energy, IPL and WPL currently expect an increase in depreciation and amortization expense in 2026 compared to 2025 due to capital projects placed in service in 2025 and 2026.
• Interest Expense - Alliant Energy, IPL and WPL currently expect an increase in interest expense in 2026 compared to 2025 due to financings completed in 2025 and planned in 2026 as discussed above.
• Allowance for Funds Used During Construction - Alliant Energy, IPL and WPL currently expect an increase in allowance for funds used during construction in 2026 compared to 2025 largely due to changes in construction work in progress balances related to construction activity on capital projects.

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LIQUIDITY AND CAPITAL RESOURCES

The liquidity and capital resources summary included in the 2024 Form 10-K has not changed materially, except as described below.

Liquidity Position - At September 30, 2025, Alliant Energy had $503 million of cash and cash equivalents, $250 million of short-term investments, $1,108 million ($550 million at the parent company, $350 million at IPL and $208 million at WPL) of available capacity under the single revolving credit facility and $4 million of available capacity at IPL under its sales of accounts receivable program.

Capital Structure - Financial capital structures at September 30, 2025 were as follows (Long-term Debt (including current maturities) (LD); Short-term Debt (SD); Common Equity (CE)):

(a) The long-term debt component of Alliant Energy’s financial capital structure includes junior subordinated notes classified as “Long-term debt, net” on Alliant Energy’s balance sheet (refer to Note 7 for additional information). 50% of the carrying amount of junior subordinated notes is excluded from the debt component of Alliant Energy’s debt-to-capital ratio used by the majority of rating agencies. Alliant Energy’s financial capital structure adjusted for the reclassification of 50% of the carrying amount of junior subordinated notes from long-term debt to common equity at September 30, 2025 was as follows: LD: 59%, CE: 40% and SD: 1%. The non-GAAP adjusted presentation reflecting this treatment is useful and relevant to investors in understanding how management and the rating agencies evaluate Alliant Energy’s capital structure.

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

Alliant Energy IPL WPL
2025 2024 2025 2024 2025 2024
Cash, cash equivalents and restricted cash, January 1 $81 $63 $29 $53 $51 $7
Cash flows from (used for):
Operating activities 900 913 289 231 573 651
Investing activities (1,605) (940) (660) (332) (530) (464)
Financing activities 1,127 794 551 804 (83) (125)
Net increase (decrease) 422 767 180 703 (40) 62
Cash, cash equivalents and restricted cash, September 30
$503 $830 $209 $756 $11 $69

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Operating Activities - The following items contributed to increased (decreased) operating activity cash flows for the nine months ended September 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Lower collections from IPL’s retail customers due to credits on customers’ bills related to production tax credits through its fuel-related cost recovery mechanism ($116) ($116) $—
Lower collections from IPL’s retail customers due to credits on customers’ bills related to the tax benefit rider (53) (53) —
Changes in income taxes paid/received (a) (50) (20) (43)
Changes in interest payments (47) (31) (13)
Restructuring and voluntary employee separation payments in 2025 (25) (11) (12)
Lower collections from IPL’s retail customers due to discontinuation of renewable energy rider in 2024 (23) (23) —
Changes in gas stored underground and prepaid gas costs (23) (10) (13)
Higher collections from IPL’s and WPL’s retail electric and IPL’s retail gas base rate increases 325 277 48
Increased collections from IPL’s and WPL’s retail customers caused by temperature impacts on electric and gas sales 40 23 17

Other (primarily due to other changes in working capital) (41) 22 (62)
($13) $58 ($78)

(a) Refer to the cash flows statements for details of renewable tax credits transferred to other corporate taxpayers during the nine months ended September 30, 2025 and 2024.

Investing Activities - The following items contributed to increased (decreased) investing activity cash flows for the nine months ended September 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Purchases of short-term investments in 2025 ($250) $— $—
(Higher) lower utility construction and acquisition expenditures (a) (207) (274) 67
Proceeds from sales of partial ownership interests in West Riverside in 2024 (123) — (123)
Changes in the amount of cash receipts on sold receivables (67) (67) —

Other (18) 13 (10)
($665) ($328) ($66)

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

Construction and Acquisition Expenditures - Construction and acquisition expenditures and financing plans are reviewed, approved and updated as part of the strategic planning process. Changes may result from a number of reasons, including changes in expected load growth, regulatory requirements, changing legislation, not obtaining favorable and acceptable regulatory approval on certain projects, changing costs of projects due to market conditions and the impact of tariffs, improvements in technology, and improvements to ensure resiliency and reliability of the electric and gas distribution systems. Alliant Energy, IPL and WPL have not yet entered into contractual commitments relating to the majority of their anticipated future construction and acquisition expenditures. As a result, they have some discretion with regard to the level and timing of these expenditures. Construction and acquisition expenditures for 2025 through 2029 are currently anticipated as follows (in millions), which are focused on adding renewable generation and energy storage projects and dispatchable gas generation projects to meet growing customer demand for electricity, including expected future data center growth from currently executed electric service agreements, and strengthening the resiliency and reliability of the electric and gas distribution systems. Alliant Energy, IPL and WPL are currently evaluating the impacts of tariffs, recently enacted legislation and additional potential large load growth customers on their resource plans, and will update their anticipated construction and acquisition expenditures as needed in the future. Cost estimates represent Alliant Energy’s, IPL’s and WPL’s portion of construction expenditures and exclude allowance for funds used during construction and capitalized interest, if applicable.

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Alliant Energy IPL WPL
2025 2026 2027 2028 2029 2025 2026 2027 2028 2029 2025 2026 2027 2028 2029
Generation:
Renewables and energy storage projects $940  $875  $1,135  $1,545  $820  $615  $445  $530  $275  $655  $310  $480  $605  $1,270  $165 
Gas projects 400  1,055  1,505  1,180  985  230  690  1,130  920  440  120  330  375  260  545 
Other 155  180  135  175  100  80  80  80  55  45  75  100  55  120  55 
Distribution:
Electric systems 620  550  545  570  615  355  275  260  265  275  265  275  285  305  340 
Gas systems 110  135  145  105  105  65  70  80  40  40  45  65  65  65  65 
Other 245  250  200  220  280  50  40  40  40  60  35  40  35  40  55 
$2,470  $3,045  $3,665  $3,795  $2,905  $1,395  $1,600  $2,120  $1,595  $1,515  $850  $1,290  $1,420  $2,060  $1,225 

Financing Activities - The following items contributed to increased (decreased) financing activity cash flows for the nine months ended September 30, 2025 compared to the same period in 2024 (in millions):

Alliant Energy IPL WPL
Higher (lower) net proceeds from issuance of long-term debt $561 $245 ($297)
(Higher) lower payments to retire long-term debt 5 (300) —
Higher (lower) capital contributions from IPL’s and WPL’s parent company, Alliant Energy — (40) 25
Net changes in the amount of commercial paper outstanding (221) (50) 327

Higher common stock dividends (22) (119) (16)

Other 10 11 3
$333 ($253) $42

FERC Financing Authorization - In August 2025, IPL received authorization from FERC to increase the long-term debt securities issuances in 2024 and 2025 to $1,950 million. The remaining capacity as of September 30, 2025 is $400 million.

Common Stock Issuances and Common Stock Dividends - Refer to Note 6 for discussion of common stock issuances by Alliant Energy in 2025 and Alliant Energy’s at-the-market offering program. Refer to “ Results of Operations ” for discussion of expected future issuances of common stock from 2026 through 2029 and common stock dividends in 2026.

Long-term Debt - Refer to Note 7 (b) for discussion of AEF’s term loan credit agreements and various issuances and/or retirements of long-term debt by Alliant Energy and IPL in 2025. Refer to “ Results of Operation s ” for discussion of expected future issuances and retirements of long-term debt by the end of 2026.

Impact of Credit Ratings on Liquidity and Collateral Obligations -
Ratings Triggers - In March 2025, Standard & Poor’s Ratings Services changed certain Alliant Energy, IPL and WPL credit ratings and outlooks, which are not expected to have a material impact on Alliant Energy’s, IPL’s and WPL’s liquidity or collateral obligations, and the current credit ratings and outlooks are as follows:

Standard & Poor’s Ratings Services
Alliant Energy: Corporate/issuer BBB+
Commercial paper A-2
Senior unsecured long-term debt BBB
Outlook Stable
IPL: Corporate/issuer BBB+
Commercial paper A-2
Senior unsecured long-term debt BBB+
Outlook Stable
WPL: Corporate/issuer A-
Commercial paper A-2
Senior unsecured long-term debt A-
Outlook Stable

Off-Balance Sheet Arrangements and Certain Financial Commitments - A summary of Alliant Energy’s and IPL’s off-balance sheet arrangements and Alliant Energy’s, IPL’s and WPL’s contractual obligations is included in the 2024 Form 10-K and has not changed materially from the items reported in the 2024 Form 10-K , except for the items described in Notes 4 , 7 and 1 3 .

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OTHER MATTERS

Critical Accounting Estimates - The summary of critical accounting estimates included in the 2024 Form 10-K has not changed materially, except as described below.

Long-Lived Assets -
Regulated Operations -
Generating Units Subject to Early Retirement - WPL currently plans to continue coal operations at Columbia Units 1 and 2 at least through 2029 as well as evaluate the potential conversion of Columbia Unit 1 and/or Unit 2 to natural gas. WPL previously planned to cease coal operations at Columbia Units 1 and 2 by the end of 2029. As a result, Alliant Energy and WPL concluded that Columbia Units 1 and 2 no longer meet the criteria to be considered probable of abandonment as of September 30, 2025. Refer to Note 3 for further discussion of Columbia Units 1 and 2.

Solar Generation Projects Recently Completed - Construction costs associated with WPL’s approximately 1,100 MW of new solar generation exceeded the construction cost estimates previously approved by the PSCW by approximately $ 205  million. In September 2025, WPL filed a settlement agreement with the PSCW for the 2026/2027 forward-looking Test Period. In November 2025, the PSCW issued an oral decision approving the settlement agreement, which includes a full return of and on these solar generation construction costs from WPL’s retail electric customers. As a result, Alliant Energy and WPL concluded that there was not a probable disallowance of the higher rate base amounts as of September 30, 2025. Refer to Note 3 for further discussion.

Retroactive Tariffs on Solar Cells and Modules - In August 2023, the U.S. Department of Commerce (DOC) issued a final ruling that found solar cells and modules produced in certain Southeast Asian countries, including Cambodia, Malaysia, Thailand and Vietnam, using parts and components produced in China, were circumventing pre-existing antidumping and countervailing duties on China. Consistent with a June 2022 Presidential Proclamation, the DOC issued rules granting duty-free treatment of solar cells and modules imported from these four countries as of June 2022 until June 2024. In August 2025, the U.S. Court of International Trade (CIT) ruled that this two-year duty suspension, as issued, was impermissible. In September 2025, this ruling from the CIT was appealed to the Federal Circuit. The CIT's order has been stayed pending appeal. Alliant Energy, IPL and WPL continue to assess the potential impact of these tariffs on previously completed solar generation projects and are currently unable to predict with certainty the future outcome or impact of these matters, including resolution of ongoing litigation.

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

Quantitative and Qualitative Disclosures About Market Risk are reported in the 2024 Form 10-K and have not changed materially.

ITEM 4. CONTROLS AND PROCEDURES

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s Chief Executive Officer, Chief Financial Officer and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures (as defined in Rule 13a-15(e) of the Securities Exchange Act of 1934, as amended) as of September 30, 2025 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the Chief Executive Officer and the Chief Financial Officer concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the quarter ended September 30, 2025.

There was no change in Alliant Energy’s, IPL’s and WPL’s internal control over financial reporting that occurred during the quarter ended September 30, 2025 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s, IPL’s or WPL’s internal control over financial reporting.

PART II. OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

None. SEC regulations require Alliant Energy, IPL and WPL to disclose information about certain proceedings arising under federal, state or local environmental provisions when a governmental authority is a party to the proceedings and such proceedings involve potential monetary sanctions that Alliant Energy, IPL and WPL reasonably believe will exceed a specified threshold. Pursuant to the SEC regulations, Alliant Energy, IPL and WPL use a threshold of $1 million for purposes of determining whether disclosure of any such proceedings is required. Applying this threshold, there are no environmental matters to disclose for this period.

ITEM 1A. RISK FACTORS

The risk factors described in Item 1A in the 2024 Form 10-K have not changed materially.

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ITEM 2. UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDS

A summary of Alliant Energy common stock repurchases for the quarter ended September 30, 2025 was as follows:

Total Number Average Price Total Number of Shares Maximum Number (or Approximate
of Shares Paid Per Purchased as Part of Dollar Value) of Shares That May
Period Purchased (a) Share Publicly Announced Plan Yet Be Purchased Under the Plan (a)
July 1 through July 31 5,948 $62.08 — N/A
August 1 through August 31 2,812 64.62 — N/A
September 1 through September 30 6 65.46 — N/A
8,766 62.90 —

(a) All shares were purchased on the open market and held in a rabbi trust under the Alliant Energy Deferred Compensation Plan. There is no limit on the number of shares of Alliant Energy common stock that may be held under the Deferred Compensation Plan, which currently does not have an expiration date.

ITEM 5. OTHER INFORMATION

(c) During the quarter ended September 30, 2025, no director or officer of Alliant Energy, IPL or WPL adopted or terminated a Rule 10b5-1 trading arrangement or non-Rule 10b5-1 trading arrangement, as each term is defined in Item 408(a) of Regulation S-K .

ITEM 6. EXHIBITS

The following Exhibits are filed herewith or incorporated herein by reference.

Exhibit Number Description
4.1 Officer’s Certificate, dated as of September 11, 2025, creating IPL’s 5.600% Senior Debentures due October 1, 2055 (incorporated by reference to Exhibit 4.1 to IPL’s Form 8-K, filed September 11, 2025 (File No. 1-4117))

4.2 Indenture, dated as of September 26, 2025, between Alliant Energy and The Bank of New York Mellon Trust Company, N.A., as trustee (incorporated by reference to Exhibit 4.1 to Alliant Energy’s Form 8-K, filed September 26, 2025 (File No. 1- 9894 ))

4.3 First Supplemental Indenture, dated as of September 26, 2025, between Alliant Energy and The Bank of New York Mellon Trust Company, N.A., as trustee, relating to the 5.750% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2056 (incorporated by reference to Exhibit 4.2 to Alliant Energy’s Form 8-K, filed September 26, 2025 (File No. 1- 9894 ))

31.1 Certification of the Chief Executive Officer for Alliant Energy

31.2 Certification of the Chief Financial Officer for Alliant Energy

31.3 Certification of the Chief Executive Officer for IPL

31.4 Certification of the Chief Financial Officer for IPL

31.5 Certification of the Chief Executive Officer for WPL

31.6 Certification of the Chief Financial Officer for WPL

32.1 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for Alliant Energy

32.2 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for IPL

32.3 Written Statement of the Chief Executive Officer and Chief Financial Officer Pursuant to 18 U.S.C.§1350 for WPL

101.INS Inline XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document
101.SCH Inline XBRL Taxonomy Extension Schema Document
101.CAL Inline XBRL Taxonomy Extension Calculation Linkbase Document
101.LAB Inline XBRL Taxonomy Extension Label Linkbase Document
101.PRE Inline XBRL Taxonomy Extension Presentation Linkbase Document
101.DEF Inline XBRL Taxonomy Extension Definition Linkbase Document
104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company have each duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized on t he 7th day of November 2025.

ALLIANT ENERGY CORPORATION
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

INTERSTATE POWER AND LIGHT COMPANY
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

WISCONSIN POWER AND LIGHT COMPANY
Registrant

By: /s/ Dylan M. Syse
Chief Accounting Officer and Controller
Dylan M. Syse (Principal Accounting Officer and Authorized Signatory)

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