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.