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v3.25.3

Regulatory Matters (Tables) | 9 Months Ended
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Sep. 30, 2025
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $1,069 |  | $989 |  | $932 |  | $870 |  | $137 |  | $119
AROs | 441 |  | 401 |  | 304 |  | 281 |  | 137 |  | 120
Pension and OPEB costs | 301 |  | 315 |  | 151 |  | 157 |  | 150 |  | 158
Assets retired early | 162 |  | 180 |  | 153 |  | 168 |  | 9 |  | 12
Non-service pension and OPEB costs | 55 |  | 51 |  | 20 |  | 19 |  | 35 |  | 32
Derivatives | 51 |  | 60 |  | 12 |  | 15 |  | 39 |  | 45
WPL’s Western Wisconsin gas distribution expansion investments | 40 |  | 42 |  | — |  | — |  | 40 |  | 42
Commodity cost recovery | 33 |  | 68 |  | 8 |  | 2 |  | 25 |  | 66
Other | 151 |  | 168 |  | 52 |  | 74 |  | 99 |  | 94
| $2,303 |  | $2,274 |  | $1,632 |  | $1,586 |  | $671 |  | $688
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $658 |  | $582 |  | $301 |  | $286 |  | $357 |  | $296
Cost of removal obligations | 351 |  | 347 |  | 206 |  | 205 |  | 145 |  | 142
Derivatives | 49 |  | 53 |  | 25 |  | 29 |  | 24 |  | 24
Other | 76 |  | 46 |  | 26 |  | 26 |  | 50 |  | 20
| $1,134 |  | $1,028 |  | $558 |  | $546 |  | $576 |  | $482
IPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $1,069 |  | $989 |  | $932 |  | $870 |  | $137 |  | $119
AROs | 441 |  | 401 |  | 304 |  | 281 |  | 137 |  | 120
Pension and OPEB costs | 301 |  | 315 |  | 151 |  | 157 |  | 150 |  | 158
Assets retired early | 162 |  | 180 |  | 153 |  | 168 |  | 9 |  | 12
Non-service pension and OPEB costs | 55 |  | 51 |  | 20 |  | 19 |  | 35 |  | 32
Derivatives | 51 |  | 60 |  | 12 |  | 15 |  | 39 |  | 45
WPL’s Western Wisconsin gas distribution expansion investments | 40 |  | 42 |  | — |  | — |  | 40 |  | 42
Commodity cost recovery | 33 |  | 68 |  | 8 |  | 2 |  | 25 |  | 66
Other | 151 |  | 168 |  | 52 |  | 74 |  | 99 |  | 94
| $2,303 |  | $2,274 |  | $1,632 |  | $1,586 |  | $671 |  | $688
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $658 |  | $582 |  | $301 |  | $286 |  | $357 |  | $296
Cost of removal obligations | 351 |  | 347 |  | 206 |  | 205 |  | 145 |  | 142
Derivatives | 49 |  | 53 |  | 25 |  | 29 |  | 24 |  | 24
Other | 76 |  | 46 |  | 26 |  | 26 |  | 50 |  | 20
| $1,134 |  | $1,028 |  | $558 |  | $546 |  | $576 |  | $482
WPL [Member] |
Regulatory Assets [Line Items] |
Regulatory Assets | Regulatory assets were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $1,069 |  | $989 |  | $932 |  | $870 |  | $137 |  | $119
AROs | 441 |  | 401 |  | 304 |  | 281 |  | 137 |  | 120
Pension and OPEB costs | 301 |  | 315 |  | 151 |  | 157 |  | 150 |  | 158
Assets retired early | 162 |  | 180 |  | 153 |  | 168 |  | 9 |  | 12
Non-service pension and OPEB costs | 55 |  | 51 |  | 20 |  | 19 |  | 35 |  | 32
Derivatives | 51 |  | 60 |  | 12 |  | 15 |  | 39 |  | 45
WPL’s Western Wisconsin gas distribution expansion investments | 40 |  | 42 |  | — |  | — |  | 40 |  | 42
Commodity cost recovery | 33 |  | 68 |  | 8 |  | 2 |  | 25 |  | 66
Other | 151 |  | 168 |  | 52 |  | 74 |  | 99 |  | 94
| $2,303 |  | $2,274 |  | $1,632 |  | $1,586 |  | $671 |  | $688
Regulatory Liabilities | Regulatory liabilities were comprised of the following items (in millions):
| Alliant Energy |  | IPL |  | WPL
| September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024 |  | September 30, 2025 |  | December 31, 2024
Tax-related | $658 |  | $582 |  | $301 |  | $286 |  | $357 |  | $296
Cost of removal obligations | 351 |  | 347 |  | 206 |  | 205 |  | 145 |  | 142
Derivatives | 49 |  | 53 |  | 25 |  | 29 |  | 24 |  | 24
Other | 76 |  | 46 |  | 26 |  | 26 |  | 50 |  | 20
| $1,134 |  | $1,028 |  | $558 |  | $546 |  | $576 |  | $482

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