ALLIANT ENERGY CORPLNT

ALLIANT ENERGY CORP PP&E Disclosure

10-KFiled Feb 20, 20263 min read
At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):
Alliant EnergyIPLWPL
202520242025202420252024
Utility:
Electric plant:
Generation and energy storage in service (a)(b)$12,757 $11,156 $6,251 $5,924 $6,506 $5,232 
Distribution in service8,418 7,811 4,691 4,344 3,727 3,467 
Other in service572 595 369 385 203 210 
Anticipated to be retired early (c)— 784 — — — 784 
Total electric plant21,747 20,346 11,311 10,653 10,436 9,693 
Gas plant in service1,938 1,863 1,020 981 918 882 
Other plant in service752 734 456456 296 278 
Accumulated depreciation (c)(6,690)(6,229)(3,574)(3,360)(3,116)(2,869)
Net plant17,747 16,714 9,213 8,730 8,534 7,984 
Leased Sheboygan Falls Energy Facility, net (d)— — — — 110 74 
Leased land for solar generation, net190 189 52 53 138 136 
Construction work in progress (e)1,742 1,215 1,166 548 576 667 
Other, net10 5 5 5 5 — 
Total utility19,689 18,123 10,436 9,336 9,363 8,861 
Non-utility and other:
Non-utility Generation, net (f)146 103 — — — — 
Corporate Services and other, net (g)509475 — — — — 
Total non-utility and other655 578 — — — — 
Total property, plant and equipment$20,344 $18,701 $10,436 $9,336 $9,363 $8,861 

(a)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 2024, the PSCW issued orders approving deferral of, and the deferral of a return on, the incremental solar generation construction costs in 2024 and 2025. In December 2025, the PSCW issued an order for the 2026/2027 forward-looking Test Period, 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 December 31, 2025.
(b)WPL’s Grant County (100 MW) and Wood County (75 MW) energy storage facilities, and IPL’s Wever (99 MW) energy storage facility, were placed in service in 2025.
(c)WPL previously received approval from MISO to retire the coal-fired Columbia Units 1 and 2. As of December 31, 2024, WPL planned to cease coal operations at Columbia Units 1 and 2 by the end of 2029, and Alliant Energy and WPL concluded that Columbia Units 1 and 2 met the criteria to be considered probable of abandonment. 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. As a result, as of December 31, 2025, Alliant Energy and WPL concluded that Columbia Units 1 and 2 no longer meet the criteria to be considered probable of abandonment.
(d)Less accumulated amortization of $120 million and $116 million for WPL as of December 31, 2025 and 2024, respectively. Refer to Note 9 for discussion of WPL’s remeasurement of this lease in 2025. 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.
(e)Alliant Energy’s and IPL’s CWIP balances were higher as of December 31, 2025, compared to December 31, 2024, primarily due to IPL’s energy storage and natural gas-fired generation projects.
(f)Less accumulated depreciation of $81 million and $78 million for Alliant Energy as of December 31, 2025 and 2024, respectively.
(g)Less accumulated depreciation of $305 million and $289 million for Alliant Energy as of December 31, 2025 and 2024, respectively.
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Historical Timeline

Fiscal YearFiled
2025Feb 20, 2026Showing above
2024Feb 21, 2025
2023Feb 16, 2024
2022Feb 24, 2023
2021Feb 18, 2022
2020Feb 19, 2021
2019Feb 21, 2020
2018Feb 22, 2019
2017Feb 23, 2018
2016Feb 24, 2017
2015Feb 24, 2016

About PP&E Disclosures

The PP&E disclosure details a company's physical asset base — land, buildings, machinery, and equipment — along with the depreciation methods and useful life assumptions that determine how these costs flow through the income statement. Capitalization policy thresholds reveal management's judgment on the boundary between expense and asset, directly affecting both reported earnings and asset values.

Key signals: changes in estimated useful lives or depreciation methods can materially shift reported earnings without any operational change. Compare capital expenditures against depreciation expense — when capex consistently trails depreciation, the asset base may be aging and underinvested. Watch for large asset impairments or write-downs that signal overvalued carrying amounts. Asset retirement obligations reveal future environmental or decommissioning costs that are often underappreciated. Compare PP&E intensity (PP&E-to-revenue) against industry peers to assess capital efficiency and competitive positioning.

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