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v3.22.4

Debt | 12 Months Ended
--- | ---
Dec. 31, 2022
Debt Instrument [Line Items] |
Debt | DEBT(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, 2022, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2026, totaled $1 billion ($500 million for Alliant Energy at the parent company level, $100 million for IPL and $400 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. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
December 31 | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Amount outstanding | $642 |  | $515 |  | $— |  | $— |  | $290 |  | $236
Weighted average interest rates | 4.6% |  | 0.2% |  | N/A |  | N/A |  | 4.5% |  | 0.2%
Available credit facility capacity | $358 |  | $485 |  | $100 |  | $250 |  | $110 |  | $64
| Alliant Energy |  | IPL |  | WPL
For the year ended | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Maximum amount outstanding (based on daily outstanding balances) | $665 |  | $648 |  | $— |  | $19 |  | $325 |  | $320
Average amount outstanding (based on daily outstanding balances) | $411 |  | $459 |  | $— |  | $— |  | $153 |  | $172
Weighted average interest rates | 2.1% |  | 0.2% |  | —% |  | 0.2% |  | 1.6% |  | 0.1%
(b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2022 |  | 2021
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures (a): |  |  |  |  |  |  |  |  |  |  |
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 | 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 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.5%, due 2049 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.1%, due 2051 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
| 3,675 |  |  | 3,675 |  |  | — |  |  | 3,675 |  |  | 3,675 |  |  | — |
Debentures (a): |  |  |  |  |  |  |  |  |  |  |
3.05%, due 2027 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3%, due 2029 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
1.95%, due 2031 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3.95%, due 2032 (b) | 600 |  |  | — |  |  | 600 |  |  | — |  |  | — |  |  | — |
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 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
3.65%, due 2050 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
2.25% (Retired in 2022) | — |  |  | — |  |  | — |  |  | 250 |  |  | — |  |  | 250 |
| 2,800 |  |  | — |  |  | 2,800 |  |  | 2,450 |  |  | — |  |  | 2,450 |
Other: |  |  |  |  |  |  |  |  |  |  |
AEF 3.75% senior notes, due 2023 (with Alliant Energy as guarantor) (a) | 400 |  |  | — |  |  | — |  |  | 400 |  |  | — |  |  | — |
AEF term loan credit agreement through March 2024, 5% at December 31, 2022 (with Alliant Energy as guarantor) (c) | 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 |  |  | — |  |  | — |
AEF 3.6% senior notes, due 2032 (with Alliant Energy as guarantor) (a)(d) | 350 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Sheboygan Power, LLC 5.06% senior secured notes, due 2023 to 2024 (secured by the Sheboygan Falls Energy Facility and related assets) (a) | 17 |  |  | — |  |  | — |  |  | 24 |  |  | — |  |  | — |
AEF term loan credit agreement, 1% at December 31, 2021 (with Alliant Energy as guarantor) (Retired in 2022) | — |  |  | — |  |  | — |  |  | 300 |  |  | — |  |  | — |
Corporate Services 3.45% senior notes (Retired in 2022) | — |  |  | — |  |  | — |  |  | 75 |  |  | — |  |  | — |
Other, 1% at December 31, 2022, due 2023 to 2025 | 1 |  |  | — |  |  | — |  |  | 1 |  |  | — |  |  | — |
| 1,668 |  |  | — |  |  | — |  |  | 1,300 |  |  | — |  |  | — |
Subtotal | 8,143 |  |  | 3,675 |  |  | 2,800 |  |  | 7,425 |  |  | 3,675 |  |  | 2,450 |
Current maturities | (408) |  |  | — |  |  | — |  |  | (633) |  |  | — |  |  | (250) |
Unamortized debt issuance costs | (45) |  |  | (21) |  |  | (19) |  |  | (42) |  |  | (23) |  |  | (15) |
Unamortized debt (discount) and premium, net | (22) |  |  | (8) |  |  | (11) |  |  | (15) |  |  | (9) |  |  | (6) |
Long-term debt, net (e) | $7,668 |  |  | $3,646 |  |  | $2,770 |  |  | $6,735 |  |  | $3,643 |  |  | $2,179 |
(a)Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. (b)In August 2022, WPL issued $600 million of 3.95% debentures due 2032. The debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of WPL’s solar EGUs. (c)In March 2022, AEF entered into a $300 million variable rate term loan credit agreement and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in March 2022. In December 2022, AEF increased the amount outstanding under the new term loan credit agreement by $100 million and used the additional borrowings to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026. Under the terms of the swap, AEF exchanged variable rate borrowings for a fixed rate of 3.93%. (d)In February 2022, AEF issued $350 million of 3.6% senior notes due 2032. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. (e)There were no significant sinking fund requirements related to the outstanding long-term debt. In December 2022, AEF entered into a $50 million variable rate term loan credit agreement (with Alliant Energy as guarantor), which expires in January 2024. AEF received the proceeds from the issuance in January 2023, and used the borrowings under this agreement to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. Five-Year Schedule of Long-term Debt Maturities - At December 31, 2022, long-term debt maturities for 2023 through 2027 were as follows (in millions):
| 2023 |  | 2024 |  | 2025 |  | 2026 |  | 2027
IPL | $— |  | $500 |  | $300 |  | $— |  | $—
WPL | — |  | — |  | — |  | — |  | 300
AEF | 408 |  | 409 |  | — |  | 200 |  | —
Alliant Energy | $408 |  | $909 |  | $300 |  | $200 |  | $300
Fair Value of Long-term Debt - Refer to Note 16 for information on the fair value of long-term debt outstanding.
IPL [Member] |
Debt Instrument [Line Items] |
Debt | DEBT(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, 2022, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2026, totaled $1 billion ($500 million for Alliant Energy at the parent company level, $100 million for IPL and $400 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. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
December 31 | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Amount outstanding | $642 |  | $515 |  | $— |  | $— |  | $290 |  | $236
Weighted average interest rates | 4.6% |  | 0.2% |  | N/A |  | N/A |  | 4.5% |  | 0.2%
Available credit facility capacity | $358 |  | $485 |  | $100 |  | $250 |  | $110 |  | $64
| Alliant Energy |  | IPL |  | WPL
For the year ended | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Maximum amount outstanding (based on daily outstanding balances) | $665 |  | $648 |  | $— |  | $19 |  | $325 |  | $320
Average amount outstanding (based on daily outstanding balances) | $411 |  | $459 |  | $— |  | $— |  | $153 |  | $172
Weighted average interest rates | 2.1% |  | 0.2% |  | —% |  | 0.2% |  | 1.6% |  | 0.1%
(b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2022 |  | 2021
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures (a): |  |  |  |  |  |  |  |  |  |  |
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 | 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 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.5%, due 2049 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.1%, due 2051 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
| 3,675 |  |  | 3,675 |  |  | — |  |  | 3,675 |  |  | 3,675 |  |  | — |
Debentures (a): |  |  |  |  |  |  |  |  |  |  |
3.05%, due 2027 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3%, due 2029 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
1.95%, due 2031 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3.95%, due 2032 (b) | 600 |  |  | — |  |  | 600 |  |  | — |  |  | — |  |  | — |
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 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
3.65%, due 2050 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
2.25% (Retired in 2022) | — |  |  | — |  |  | — |  |  | 250 |  |  | — |  |  | 250 |
| 2,800 |  |  | — |  |  | 2,800 |  |  | 2,450 |  |  | — |  |  | 2,450 |
Other: |  |  |  |  |  |  |  |  |  |  |
AEF 3.75% senior notes, due 2023 (with Alliant Energy as guarantor) (a) | 400 |  |  | — |  |  | — |  |  | 400 |  |  | — |  |  | — |
AEF term loan credit agreement through March 2024, 5% at December 31, 2022 (with Alliant Energy as guarantor) (c) | 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 |  |  | — |  |  | — |
AEF 3.6% senior notes, due 2032 (with Alliant Energy as guarantor) (a)(d) | 350 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Sheboygan Power, LLC 5.06% senior secured notes, due 2023 to 2024 (secured by the Sheboygan Falls Energy Facility and related assets) (a) | 17 |  |  | — |  |  | — |  |  | 24 |  |  | — |  |  | — |
AEF term loan credit agreement, 1% at December 31, 2021 (with Alliant Energy as guarantor) (Retired in 2022) | — |  |  | — |  |  | — |  |  | 300 |  |  | — |  |  | — |
Corporate Services 3.45% senior notes (Retired in 2022) | — |  |  | — |  |  | — |  |  | 75 |  |  | — |  |  | — |
Other, 1% at December 31, 2022, due 2023 to 2025 | 1 |  |  | — |  |  | — |  |  | 1 |  |  | — |  |  | — |
| 1,668 |  |  | — |  |  | — |  |  | 1,300 |  |  | — |  |  | — |
Subtotal | 8,143 |  |  | 3,675 |  |  | 2,800 |  |  | 7,425 |  |  | 3,675 |  |  | 2,450 |
Current maturities | (408) |  |  | — |  |  | — |  |  | (633) |  |  | — |  |  | (250) |
Unamortized debt issuance costs | (45) |  |  | (21) |  |  | (19) |  |  | (42) |  |  | (23) |  |  | (15) |
Unamortized debt (discount) and premium, net | (22) |  |  | (8) |  |  | (11) |  |  | (15) |  |  | (9) |  |  | (6) |
Long-term debt, net (e) | $7,668 |  |  | $3,646 |  |  | $2,770 |  |  | $6,735 |  |  | $3,643 |  |  | $2,179 |
(a)Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. (b)In August 2022, WPL issued $600 million of 3.95% debentures due 2032. The debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of WPL’s solar EGUs. (c)In March 2022, AEF entered into a $300 million variable rate term loan credit agreement and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in March 2022. In December 2022, AEF increased the amount outstanding under the new term loan credit agreement by $100 million and used the additional borrowings to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026. Under the terms of the swap, AEF exchanged variable rate borrowings for a fixed rate of 3.93%. (d)In February 2022, AEF issued $350 million of 3.6% senior notes due 2032. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. (e)There were no significant sinking fund requirements related to the outstanding long-term debt. In December 2022, AEF entered into a $50 million variable rate term loan credit agreement (with Alliant Energy as guarantor), which expires in January 2024. AEF received the proceeds from the issuance in January 2023, and used the borrowings under this agreement to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. Five-Year Schedule of Long-term Debt Maturities - At December 31, 2022, long-term debt maturities for 2023 through 2027 were as follows (in millions):
| 2023 |  | 2024 |  | 2025 |  | 2026 |  | 2027
IPL | $— |  | $500 |  | $300 |  | $— |  | $—
WPL | — |  | — |  | — |  | — |  | 300
AEF | 408 |  | 409 |  | — |  | 200 |  | —
Alliant Energy | $408 |  | $909 |  | $300 |  | $200 |  | $300
Fair Value of Long-term Debt - Refer to Note 16 for information on the fair value of long-term debt outstanding.
WPL [Member] |
Debt Instrument [Line Items] |
Debt | DEBT(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, 2022, the short-term borrowing capacity under a single credit facility agreement, which expires in December 2026, totaled $1 billion ($500 million for Alliant Energy at the parent company level, $100 million for IPL and $400 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. Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper classified as short-term debt was as follows (dollars in millions):
| Alliant Energy |  | IPL |  | WPL
December 31 | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Amount outstanding | $642 |  | $515 |  | $— |  | $— |  | $290 |  | $236
Weighted average interest rates | 4.6% |  | 0.2% |  | N/A |  | N/A |  | 4.5% |  | 0.2%
Available credit facility capacity | $358 |  | $485 |  | $100 |  | $250 |  | $110 |  | $64
| Alliant Energy |  | IPL |  | WPL
For the year ended | 2022 |  | 2021 |  | 2022 |  | 2021 |  | 2022 |  | 2021
Maximum amount outstanding (based on daily outstanding balances) | $665 |  | $648 |  | $— |  | $19 |  | $325 |  | $320
Average amount outstanding (based on daily outstanding balances) | $411 |  | $459 |  | $— |  | $— |  | $153 |  | $172
Weighted average interest rates | 2.1% |  | 0.2% |  | —% |  | 0.2% |  | 1.6% |  | 0.1%
(b) Long-Term Debt - Long-term debt, net as of December 31 was as follows (dollars in millions):
| 2022 |  | 2021
| Alliant Energy |  | IPL |  | WPL |  | Alliant Energy |  | IPL |  | WPL
Senior Debentures (a): |  |  |  |  |  |  |  |  |  |  |
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 | 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 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.5%, due 2049 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
3.1%, due 2051 | 300 |  |  | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |
| 3,675 |  |  | 3,675 |  |  | — |  |  | 3,675 |  |  | 3,675 |  |  | — |
Debentures (a): |  |  |  |  |  |  |  |  |  |  |
3.05%, due 2027 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3%, due 2029 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
1.95%, due 2031 | 300 |  |  | — |  |  | 300 |  |  | 300 |  |  | — |  |  | 300 |
3.95%, due 2032 (b) | 600 |  |  | — |  |  | 600 |  |  | — |  |  | — |  |  | — |
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 | 250 |  |  | — |  |  | 250 |  |  | 250 |  |  | — |  |  | 250 |
3.65%, due 2050 | 350 |  |  | — |  |  | 350 |  |  | 350 |  |  | — |  |  | 350 |
2.25% (Retired in 2022) | — |  |  | — |  |  | — |  |  | 250 |  |  | — |  |  | 250 |
| 2,800 |  |  | — |  |  | 2,800 |  |  | 2,450 |  |  | — |  |  | 2,450 |
Other: |  |  |  |  |  |  |  |  |  |  |
AEF 3.75% senior notes, due 2023 (with Alliant Energy as guarantor) (a) | 400 |  |  | — |  |  | — |  |  | 400 |  |  | — |  |  | — |
AEF term loan credit agreement through March 2024, 5% at December 31, 2022 (with Alliant Energy as guarantor) (c) | 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 |  |  | — |  |  | — |
AEF 3.6% senior notes, due 2032 (with Alliant Energy as guarantor) (a)(d) | 350 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Sheboygan Power, LLC 5.06% senior secured notes, due 2023 to 2024 (secured by the Sheboygan Falls Energy Facility and related assets) (a) | 17 |  |  | — |  |  | — |  |  | 24 |  |  | — |  |  | — |
AEF term loan credit agreement, 1% at December 31, 2021 (with Alliant Energy as guarantor) (Retired in 2022) | — |  |  | — |  |  | — |  |  | 300 |  |  | — |  |  | — |
Corporate Services 3.45% senior notes (Retired in 2022) | — |  |  | — |  |  | — |  |  | 75 |  |  | — |  |  | — |
Other, 1% at December 31, 2022, due 2023 to 2025 | 1 |  |  | — |  |  | — |  |  | 1 |  |  | — |  |  | — |
| 1,668 |  |  | — |  |  | — |  |  | 1,300 |  |  | — |  |  | — |
Subtotal | 8,143 |  |  | 3,675 |  |  | 2,800 |  |  | 7,425 |  |  | 3,675 |  |  | 2,450 |
Current maturities | (408) |  |  | — |  |  | — |  |  | (633) |  |  | — |  |  | (250) |
Unamortized debt issuance costs | (45) |  |  | (21) |  |  | (19) |  |  | (42) |  |  | (23) |  |  | (15) |
Unamortized debt (discount) and premium, net | (22) |  |  | (8) |  |  | (11) |  |  | (15) |  |  | (9) |  |  | (6) |
Long-term debt, net (e) | $7,668 |  |  | $3,646 |  |  | $2,770 |  |  | $6,735 |  |  | $3,643 |  |  | $2,179 |
(a)Contains optional redemption provisions which, if elected by the issuer at its sole discretion, could require material redemption premium payments by the issuer. The redemption premium payments under these optional redemption provisions are variable and dependent on applicable U.S. Treasury rates at the time of redemption. (b)In August 2022, WPL issued $600 million of 3.95% debentures due 2032. The debentures were issued as green bonds, and an amount equal to or in excess of the net proceeds were disbursed for the development and acquisition of WPL’s solar EGUs. (c)In March 2022, AEF entered into a $300 million variable rate term loan credit agreement and used the borrowings under this agreement to retire its $300 million variable rate term loan credit agreement that expired in March 2022. In December 2022, AEF increased the amount outstanding under the new term loan credit agreement by $100 million and used the additional borrowings to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. In January 2023, AEF entered into a $300 million interest rate swap maturing in January 2026. Under the terms of the swap, AEF exchanged variable rate borrowings for a fixed rate of 3.93%. (d)In February 2022, AEF issued $350 million of 3.6% senior notes due 2032. The net proceeds from the issuance were used to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. (e)There were no significant sinking fund requirements related to the outstanding long-term debt. In December 2022, AEF entered into a $50 million variable rate term loan credit agreement (with Alliant Energy as guarantor), which expires in January 2024. AEF received the proceeds from the issuance in January 2023, and used the borrowings under this agreement to reduce Alliant Energy’s outstanding commercial paper and for general corporate purposes. Five-Year Schedule of Long-term Debt Maturities - At December 31, 2022, long-term debt maturities for 2023 through 2027 were as follows (in millions):
| 2023 |  | 2024 |  | 2025 |  | 2026 |  | 2027
IPL | $— |  | $500 |  | $300 |  | $— |  | $—
WPL | — |  | — |  | — |  | — |  | 300
AEF | 408 |  | 409 |  | — |  | 200 |  | —
Alliant Energy | $408 |  | $909 |  | $300 |  | $200 |  | $300
Fair Value of Long-term Debt - Refer to Note 16 for information on the fair value of long-term debt outstanding.

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