Northern States Power 10-Q 25 Apr 24 2024 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2024	Apr. 25, 2024
Cover [Abstract]
Entity Registrant Name	NORTHERN STATES POWER CO /WI/
Entity Central Index Key	0000072909
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-03140
Entity Incorporation, State or Country Code	WI
Entity Tax Identification Number	39-0508315
Entity Address, Address Line One	1414 West Hamilton Avenue
Entity Address, City or Town	Eau Claire
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	54701
City Area Code	(715)
Local Phone Number	852-5812
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		933,000

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating revenues
Electric, non-affiliates	$ 203	$ 204
Electric, affiliates	53	50
Natural gas	54	77
Total operating revenues	310	331
Operating expenses
Electric fuel and purchased power, non-affiliates	4	4
Purchased power, affiliates	103	103
Cost of natural sold and transported	24	46
Operating and maintenance expenses	56	58
Conservation program expenses	3	3
Depreciation and amortization	45	41
Taxes (other than income taxes)	9	8
Total operating expenses	244	263
Operating income	66	68
Allowance for funds used during construction — equity	3	2
Interest charges and financing costs
Interest charges and other financing costs	14	13
Allowance for funds used during construction — debt	(1)	(1)
Total interest charges and financing costs	13	12
Income before income taxes	56	58
Income tax expense	13	13
Net income	$ 43	$ 45

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net income	$ 43	$ 45
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	46	42
Deferred income taxes	3	(2)
Allowance for equity funds used during construction	3	2
Provision for bad debts	1	2
Changes in operating assets and liabilities:
Accounts receivable	(13)	(16)
Accrued unbilled revenues	9	20
Inventories	3	15
Other current assets	5	13
Accounts payable	(7)	(10)
Net regulatory assets and liabilities	(1)	17
Other current liabilities	5	0
Pension and other employee benefit obligations	(7)	(3)
Other, net	2	1
Net cash provided by operating activities	86	122
Investing activities
Capital/construction expenditures	(121)	(101)
Net cash used in investing activities	(121)	(101)
Financing activities
Repayments of short-term borrowings, net	(60)	(35)
Borrowings under utility money pool arrangement	130	0
Repayments under utility money pool arrangement	(111)	0
Capital contributions from parent	106	36
Dividends paid to parent	(25)	(23)
Net cash provided (used in) by financing activities	40	(22)
Net change in cash, cash equivalents and restricted cash	5	(1)
Cash, cash equivalents and restricted cash at beginning of period	6	2
Cash, cash equivalents and restricted cash at end of period	11	1
Supplemental disclosure of cash flow information:
Cash paid for interest (net of amounts capitalized)	(12)	(13)
Cash paid for income taxes, net	(7)	(4)
Supplemental disclosure of non-cash investing and financing transactions:
Accrued property, plant and equipment additions	33	33
Inventory transfers to property, plant and equipment	2	2
Allowance for equity funds used during construction	$ 3	$ 2

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Current assets
Cash and cash equivalents	$ 11	$ 6
Accounts receivable, net	90	89
Accrued unbilled revenues	53	63
Inventories	24	29
Regulatory assets	23	24
Prepaid taxes	21	28
Prepayments and other	7	6
Total current assets	229	245
Property, Plant and Equipment, Net [Abstract]
Property, plant and equipment, net	3,332	3,237
Other assets
Regulatory assets	181	185
Other	3	3
Total other assets	184	188
Total assets	3,745	3,670
Current liabilities
Current portion of long-term debt	200	200
Short-term debt	0	60
Borrowings under utility money pool arrangement	19	0
Dividends payable to parent	18	25
Regulatory liabilities	41	42
Taxes accrued	19	16
Accrued interest	13	13
Other	24	23
Total current liabilities	415	464
Deferred credits and other liabilities
Deferred income taxes	336	330
Deferred investment tax credits	5	5
Regulatory liabilities	412	407
Customer advances	26	25
Pension and employee benefit obligations	20	27
Other	34	35
Total deferred credits and other liabilities	833	829
Commitments and contingencies
Capitalization
Long-term debt	1,011	1,011
Common stock — 1,000,000 shares authorized of $100 par value; 933,000 shares outstanding at March 31, 2024 and Dec. 31, 2023, respectively	$ 93	$ 93
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share)	$ 100	$ 100
Common stock, shares outstanding (in shares)	933,000	933,000
Additional paid in capital	$ 938	$ 843
Retained earnings	455	430
Total common stockholder's equity	1,486	1,366
Total liabilities and equity	3,745	3,670
Related Party
Current liabilities
Accounts payable	61	64
Affiliated Entity
Current liabilities
Accounts payable	$ 20	$ 21

CONSOLIDATED STATEMENTS OF COMM

CONSOLIDATED STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Millions	Total	Common stock	Additional Paid In Capital	Retained Earnings
Balance (in shares) at Dec. 31, 2022		933,000
Beginning Balance at Dec. 31, 2022	$ 1,259	$ 93	$ 761	$ 405
Increase (Decrease) in Stockholder's Equity
Net income	45			45
Common dividends declared to parent	(24)			(24)
Contribution of capital by parent	30		30
Balance (in shares) at Mar. 31, 2023		933,000
Ending Balance at Mar. 31, 2023	$ 1,310	$ 93	791	426
Balance (in shares) at Dec. 31, 2023	933,000	933,000
Beginning Balance at Dec. 31, 2023	$ 1,366	$ 93	843	430
Increase (Decrease) in Stockholder's Equity
Net income	43			43
Common dividends declared to parent	(18)			(18)
Contribution of capital by parent	$ 95		95
Balance (in shares) at Mar. 31, 2024	933,000	933,000
Ending Balance at Mar. 31, 2024	$ 1,486	$ 93	$ 938	$ 455

Management's Opinion

Management's Opinion	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Management's Opinion	In the opinion of management, the accompanying unaudited consolidated financial statements contain all adjustments necessary to present fairly, in accordance with GAAP, the financial position of NSP-Wisconsin and its subsidiaries as of March 31, 2024 and Dec. 31, 2023; the results of NSP-Wisconsin's operations, including the components of net income, cash flows, and changes in stockholder's equity for the three months ended March 31, 2024 and 2023. All adjustments are of a normal, recurring nature, except as otherwise disclosed. Management has also evaluated the impact of events occurring after March 31, 2024 up to the date of issuance of these consolidated financial statements. These statements contain all necessary adjustments and disclosures resulting from that evaluation. The Dec. 31, 2023 balance sheet information has been derived from the audited 2023 consolidated financial statements included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023. Notes to the consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC for Quarterly Reports on Form 10-Q. Certain information and note disclosures normally included in financial statements prepared in accordance with GAAP on an annual basis have been condensed or omitted pursuant to such rules and regulations. For further information, refer to the consolidated financial statements and notes thereto included in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023, filed with the SEC on Feb. 21, 2024. Due to the seasonality of NSP-Wisconsin’s electric and natural gas sales, interim results are not necessarily an appropriate base from which to project annual results.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	The significant accounting policies set forth in Note 1 to the consolidated financial statements in the NSP-Wisconsin Annual Report on Form 10-K for the year ended Dec. 31, 2023 appropriately represent, in all material respects, the current status of accounting policies and are incorporated herein by reference.

Accounting Pronouncements

Accounting Pronouncements	3 Months Ended
	Mar. 31, 2024
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Pronouncements	Recently Issued Segment Reporting — In November 2023, the FASB issued ASU 2023-07 – Segment Reporting (Topic 280) – Improvements to Reportable Segment Disclosures , which extends the existing requirements for annual disclosures to quarterly periods, and requires that both annual and quarterly disclosures present segment expenses using line items consistent with information regularly provided to the chief operating decision maker. The ASU is effective for annual periods beginning after Dec. 15, 2023 and quarterly periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements. Income Taxes — In December 2023, the FASB issued ASU 2023-09 – Income Taxes (Topic 740) – Improvements to Income Tax Disclosures , with new disclosure requirements including presentation of prescribed line items in the effective tax rate reconciliation and disclosures regarding state and local tax payments. The ASU is effective for annual periods beginning after Dec. 15, 2024, and Xcel Energy does not expect implementation of the new disclosure guidance to have a material impact to its consolidated financial statements. Climate-Related Disclosures — In March 2024, the SEC issued Final Rule 33-11275 – The Enhancement and Standardization of Climate-Related Disclosures for Investors. This rule requires registrants to provide standardized disclosures in Form 10-K related to climate-related risks, Scope 1 and 2 greenhouse gas emissions, as well as to include in a footnote to the consolidated financial statements the financial impact of severe weather events and other natural conditions. The rule requires implementation in phases between 2025 and 2033. In April 2024, the SEC announced that it would voluntarily stay its final climate disclosure rules pending judicial review. Xcel Energy does not expect implementation of the new guidance to have a material impact on the consolidated financial statements.

Selected Balance Sheet Data

Selected Balance Sheet Data	3 Months Ended
	Mar. 31, 2024
Balance Sheet Related Disclosures [Abstract]
Selected Balance Sheet Data	(Millions of dollars) March 31, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 98 $ 98 Less allowance for bad debts (8) (9) Accounts receivable, net $ 90 $ 89 (Millions of dollars) March 31, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 12 $ 11 Fuel 10 10 Natural gas 2 8 Total inventories $ 24 $ 29 (Millions of dollars) March 31, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 3,895 $ 3,845 Natural gas plant 504 502 Common and other property 287 278 Construction work in progress 306 252 Total property, plant and equipment 4,992 4,877 Less accumulated depreciation (1,660) (1,640) Property, plant and equipment, net $ 3,332 $ 3,237

Borrowings and Other Financing

Borrowings and Other Financing Instruments	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Borrowings and Other Financing Instruments	Short-Term Borrowings NSP-Wisconsin meets its short-term liquidity requirements primarily through the issuance of commercial paper and borrowings under its credit facility and the money pool. Money Pool — Xcel Energy Inc. and its utility subsidiaries have established a money pool arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Xcel Energy Inc. may make investments in the utility subsidiaries at market-based interest rates; however, the money pool arrangement does not allow the utility subsidiaries to make investments in Xcel Energy Inc. Money pool borrowings: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 150 $ 150 Amount outstanding at period end 19 — Average amount outstanding 12 6 Maximum amount outstanding 54 43 Weighted average interest rate, computed on a daily basis 5.33 % 4.98 % Weighted average interest rate at period end 5.33 N/A Commercial Paper — Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 150 $ 150 Amount outstanding at period end — 60 Average amount outstanding 41 15 Maximum amount outstanding 99 93 Weighted average interest rate, computed on a daily basis 5.49 % 4.85 % Weighted average interest rate at period end N/A 5.50 Letters of Credit — NSP-Wisconsin uses letters of credit, generally with terms of one year, to provide financial guarantees for certain obligations. At both March 31, 2024 and Dec. 31, 2023, there we re immaterial l etters of credit outstanding under the credit facility. Revolving Credit Facility — In order to issue its commercial paper, NSP-Wisconsin must have a revolving credit facility equal to or greater than the commercial paper borrowing limit and cannot issue commercial paper exceeding available capacity under this credit facility. The credit facility provides short-term financing in the form of notes payable to banks, letters of credit and back-up support for commercial paper borrowings. NSP-Wisconsin has the right to request an extension of the revolving credit facility termination date for an additional one-year period. All extension requests are subject to majority bank group approval. As of March 31, 2024, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Outstanding (b) Available $ 150 $ — $ 150 (a) Expires in September 2027. (b) Includes outstanding commercial paper. All credit facility ban k borrowings, outstanding letters of credit and outstanding commercial paper reduce the available capacity under the credit facility. NSP-Wisconsin had no direct advances on the credit facility outstanding at March 31, 2024 and Dec. 31, 2023. Other Short-Term Borrowings — Clearwater Investments, Inc., a NSP-Wisconsin subsidiary, had an immaterial note payable to Xcel Energy Inc. as of March 31, 2024 and Dec. 31, 2023, respectively.

Revenues

Revenues	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenues	Revenue is classified by the type of goods/services rendered and market/customer type. NSP-Wisconsin’s operating revenues consisted of the following: Three Months Ended (Millions of Dollars) Electric Natural Gas Total Major revenue types Revenue from contracts with customers: Residential $ 77 $ 30 $ 107 C&I 118 22 140 Other 2 — 2 Total retail 197 52 249 Interchange and other 56 1 57 Total revenue from contracts with customers 253 53 306 Alternative revenue and other 3 1 4 Total revenues $ 256 $ 54 $ 310 Three Months Ended (Millions of Dollars) Electric Natural Gas Total Major revenue types Revenue from contracts with customers: Residential $ 82 $ 41 $ 123 C&I 120 34 154 Other 2 — 2 Total retail 204 75 279 Interchange and other 47 1 48 Total revenue from contracts with customers 251 76 327 Alternative revenue and other 3 1 4 Total revenues $ 254 $ 77 $ 331

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes Reconciliation between the statutory rate and effective tax rate: Three Months Ended March 31 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 6.2 6.2 (Decreases) increases: Plant regulatory differences (a) (4.3) (3.5) Other (net) 0.3 (1.3) Effective income tax rate 23.2 % 22.4 % (a)

Fair Value of Financial Assets

Fair Value of Financial Assets and Liabilities	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value of Financial Assets and Liabilities	7. Fair Value of Financial Assets and Liabilities Fair Value Measurements Accounting guidance for fair value measurements and disclosures provides a hierarchical framework for disclosing the observability of the inputs utilized in measuring assets and liabilities at fair value. • Level 1 — Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. The types of assets and liabilities included in Level 1 are actively traded instruments with observable actual trading prices. • Level 2 — Pricing inputs are other than actual trading prices in active markets, but are either directly or indirectly observable as of the reporting date. The types of assets and liabilities included in Level 2 are typically either comparable to actively traded securities or contracts or priced with models using highly observable inputs. • Level 3 — Significant inputs to pricing have little or no observability as of the reporting date. The types of assets and liabilities included in Level 3 include those valued with models requiring significant judgment or estimation. Specific valuation methods include: Commodity Derivatives — Methods used to measure the fair value of commodity derivative forwards and options utilize forward prices and volatilities, as well as pricing adjustments for specific delivery locations, and are generally assigned a Level 2 classification. When contracts relate to inactive delivery locations or extend to periods beyond those readily observable on active exchanges, the significance of the use of less observable inputs on a valuation is evaluated, and may result in Level 3 classification. Derivative Activities and Fair Value Measurements NSP-Wisconsin enters into derivative instruments, including forward contracts, futures, swaps and options, to manage risk in connection with changes in utility commodity prices. Commodity Derivatives — NSP-Wisconsin enters into derivative instruments to manage variability of future cash flows from changes in commodity prices in its electric and natural gas operations. This could include the purchase or sale of natural gas to generate electric energy and natural gas for resale. As of March 31, 2024, NSP-Wisconsin had no commodity contracts designated as cash flow hedges. Consideration of Credit Risk and Concentrations — NSP-Wisconsin continuously monitors the creditworthiness of counterparties to its interest rate derivatives and commodity derivative contracts prior to settlement, and assesses each counterparty’s ability to perform on the transactions set forth in the contracts. Impact of credit risk was immaterial to the fair value of unsettled commodity derivatives presented on the consolidated balance sheets. Recurring Derivative Fair Value Measurements Impact of derivative activity: Changes in the fair value of natural gas commodity derivatives resulted in immaterial and $1 million of net gains for the three months ended March 31, 2024 and 2023, respectively, which were recognized as regulatory assets and liabilities. The classification as a regulatory asset or liability is based on commission approved regulatory recovery mechanisms. During the three months ended March 31, 2024 and 2023, $1 million and $2 million, respectively, of pre-tax losses were recognized during the period related to option premium amortization subject to natural gas cost recovery mechanisms and reclassified out of income to a regulatory asset, as appropriate. NSP-Wisconsin had immaterial outstanding derivative assets or liabilities measured at fair value as of March 31, 2024 and Dec. 31, 2023. Fair Value of Long-Term Debt As of March 31, 2024, other financial instruments for which the carrying amount did not equal fair value: March 31, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,211 $ 1,104 $ 1,211 $ 1,117 Fair value of NSP-Wisconsin’s long-term debt is estimated based on recent trades and observable spreads from benchmark interest rates for similar securities. Fair value estimates are based on information available to management as of March 31, 2024 and Dec. 31, 2023, and given the observability of the inputs, fair values presented for long-term debt were assigned as Level 2.

Benefit Plans and Other Postret

Benefit Plans and Other Postretirement Benefits	3 Months Ended
	Mar. 31, 2024
Retirement Benefits [Abstract]
Benefit Plans and Other Postretirement Benefits	Components of Net Periodic Benefit Cost Three Months Ended March 31 2024 2023 (Millions of Dollars) Pension Benefits Service cost $ 1 $ 1 Interest cost (a) 2 2 Expected return on plan assets (a) (2) (2) Net periodic benefit cost $ 1 $ 1 (a) The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Legal NSP-Wisconsin is involved in various litigation matters in the ordinary course of business. The assessment of whether a loss is probable or is a reasonable possibility, and whether the loss or a range of loss is estimable, often involves a series of complex judgments about future events. Management maintains accruals for losses probable of being incurred and subject to reasonable estimation. Management is sometimes unable to estimate an amount or range of a reasonably possible loss in certain situations, including but not limited to when (1) the damages sought are indeterminate, (2) the proceedings are in the early stages, or (3) the matters involve novel or unsettled legal theories. In such cases, there is considerable uncertainty regarding the timing or ultimate resolution, including a possible eventual loss. For current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, would have a material effect on NSP-Wisconsin’s consolidated financial statements. Legal fees are generally expensed as incurred. Gas Trading Litigation — e prime is a wholly owned subsidiary of Xcel Energy. e prime was in the business of natural gas trading and marketing but has not engaged in natural gas trading or marketing activities since 2003. Multiple lawsuits involving multiple plaintiffs seeking monetary damages were commenced against e prime and its affiliates, including Xcel Energy, between 2003 and 2009 alleging fraud and anticompetitive activities in conspiring to restrain the trade of natural gas and manipulate natural gas prices. Cases were all consolidated in the U.S. District Court in Nevada. One case remains active which includes a multi-district litigation matter consisting of a Wisconsin purported class (Arandell Corp.). The Court issued a ruling in June 2022 granting plaintiffs’ class certification. In April 2023, the Seventh Circuit Court of Appeals heard the defendants’ appeal challenging whether the district court properly assessed class certification. A decision relating to class certification is expected imminently. Xcel Energy considers the reasonably possible loss associated with this litigation to be immaterial. Rate Matters NSP-Wisconsin is involved in various regulatory proceedings arising in the ordinary course of business. Until resolution, typically in the form of a rate order, uncertainties may exist regarding the ultimate rate treatment for certain activities and transactions. Amounts have been recognized for probable and reasonably estimable losses that may result. Unless otherwise disclosed, any reasonably possible range of loss in excess of any recognized amount is not expected to have a material effect on the financial statements. Environmental New and changing federal and state environmental mandates can create financial liabilities for NSP-Wisconsin, which are normally recovered through the regulated rate process. Site Remediation Various federal and state environmental laws impose liability where hazardous substances or other regulated materials have been released to the environment. NSP-Wisconsin may sometimes pay all or a portion of the cost to remediate sites where past activities of their predecessors or other parties have caused environmental contamination. Environmental contingencies could arise from various situations, including sites of former MGPs; and third-party sites, such as landfills, for which NSP-Wisconsin is alleged to have sent wastes to that site. MGP, Landfill and Disposal Sites NSP-Wisconsin is investigating, remediating or performing post-closure actions at one MGP, landfill or other disposal sites across its service territories. NSP-Wisconsin has recognized approximately $13 million of costs/liabilities from final resolution of these issues, however, the outcome and timing are unknown. In addition, there may be regulatory recovery, insurance recovery and/or recovery from other potentially responsible parties, offsetting a portion of costs incurred. Environmental Requirements — Water and Waste Federal Clean Water Act Section 316(b) — The Federal Clean Water Act requires the EPA to regulate cooling water intake structures to assure they reflect the best technology available for minimizing impingement and entrainment of aquatic species. NSP-Wisconsin estimates capital expenditures of approximately $5 million may be required to comply with the requirements. NSP-Wisconsin believes two plants could be required to make improvements to reduce impingement and entrainment. NSP-Wisconsin anticipates these costs will be recoverable through regulatory mechanisms. Environmental Requirements — Air Clean Air Act NOx Allowance Allocations — In June 2023, the EPA published final regulations under the "Good Neighbor" provisions of the Clean Air Act. The final rule applies to generation facilities in Wisconsin, as well as other states outside of our service territory. The rule establishes an allowance trading program for NOx that will impact NSP-Wisconsin’s fossil fuel-fired electric generating facilities. Subject facilities will have to secure additional allowances, install NOx controls and/or develop a strategy of operations that utilizes the existing allowance allocations. Guidelines are also established for allowance banking and emission limit backstops. While the financial impacts of the final rule are uncertain and dependent on market forces and anticipated generation, NSP-Wisconsin anticipates the costs would be recoverable through regulatory mechanisms.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2024
Segment Reporting [Abstract]
Segment Information	NSP-Wisconsin evaluates performance based on profit or loss generated from the product or service provided. These segments are managed separately because the revenue streams are dependent upon regulated rate recovery, which is separately determined for each segment. NSP-Wisconsin has the following reportable segments: • Regulated Electric — The regulated electric utility segment generates electricity, which is transmitted and distributed in Wisconsin and Michigan. • Regulated Natural Gas — The regulated natural gas utility segment purchases, transports, stores and distributes natural gas in portions of Wisconsin and Michigan. Asset and capital expenditure information is not provided for NSP-Wisconsin's reportable segments. As an integrated electric and natural gas utility, NSP-Wisconsin operates significant assets that are not dedicated to a specific business segment. Reporting assets and capital expenditures by business segment would require arbitrary and potentially misleading allocations, which may not necessarily reflect the assets that would be required for the operation of the business segments on a stand-alone basis. Certain costs, such as common depreciation, common O&M expenses and interest expense are allocated based on cost causation allocators across each segment. In addition, a general allocator is used for certain general and administrative expenses, including office supplies, rent, property insurance and general advertising. NSP-Wisconsin's segment information: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Regulated Electric Total revenues (a) $ 256 $ 254 Net income 33 33 Regulated Natural Gas Total revenues $ 54 $ 77 Net income 10 11 All Other Net income $ — $ 1 Consolidated Total Total revenues (a) $ 310 $ 331 Net income 43 45 (a) Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net income	$ 43	$ 45

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Selected Balance Sheet Data (Ta

Selected Balance Sheet Data (Tables)	3 Months Ended
	Mar. 31, 2024
Balance Sheet Related Disclosures [Abstract]
Accounts Receivable, Net	(Millions of dollars) March 31, 2024 Dec. 31, 2023 Accounts receivable, net Accounts receivable $ 98 $ 98 Less allowance for bad debts (8) (9) Accounts receivable, net $ 90 $ 89
Inventories	(Millions of dollars) March 31, 2024 Dec. 31, 2023 Inventories Materials and supplies $ 12 $ 11 Fuel 10 10 Natural gas 2 8 Total inventories $ 24 $ 29
Property, Plant and Equipment, Net	(Millions of dollars) March 31, 2024 Dec. 31, 2023 Property, plant and equipment, net Electric plant $ 3,895 $ 3,845 Natural gas plant 504 502 Common and other property 287 278 Construction work in progress 306 252 Total property, plant and equipment 4,992 4,877 Less accumulated depreciation (1,660) (1,640) Property, plant and equipment, net $ 3,332 $ 3,237

Borrowings and Other Financin_2

Borrowings and Other Financing Instruments (Tables)	3 Months Ended
	Mar. 31, 2024
Borrowings and Other Financing Instruments [Abstract]
Credit Facilities	As of March 31, 2024, NSP-Wisconsin had the following committed revolving credit facility available (in millions of dollars): Credit Facility (a) Outstanding (b) Available $ 150 $ — $ 150 (a) Expires in September 2027. (b) Includes outstanding commercial paper.
Money Pool
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Money pool borrowings: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 150 $ 150 Amount outstanding at period end 19 — Average amount outstanding 12 6 Maximum amount outstanding 54 43 Weighted average interest rate, computed on a daily basis 5.33 % 4.98 % Weighted average interest rate at period end 5.33 N/A
Commercial Paper
Borrowings and Other Financing Instruments [Abstract]
Short-Term Borrowings	Commercial paper outstanding: (Amounts in Millions, Except Interest Rates) Three Months Ended March 31, 2024 Year Ended Dec. 31, 2023 Borrowing limit $ 150 $ 150 Amount outstanding at period end — 60 Average amount outstanding 41 15 Maximum amount outstanding 99 93 Weighted average interest rate, computed on a daily basis 5.49 % 4.85 % Weighted average interest rate at period end N/A 5.50

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Disaggregation of revenue	NSP-Wisconsin’s operating revenues consisted of the following: Three Months Ended (Millions of Dollars) Electric Natural Gas Total Major revenue types Revenue from contracts with customers: Residential $ 77 $ 30 $ 107 C&I 118 22 140 Other 2 — 2 Total retail 197 52 249 Interchange and other 56 1 57 Total revenue from contracts with customers 253 53 306 Alternative revenue and other 3 1 4 Total revenues $ 256 $ 54 $ 310 Three Months Ended (Millions of Dollars) Electric Natural Gas Total Major revenue types Revenue from contracts with customers: Residential $ 82 $ 41 $ 123 C&I 120 34 154 Other 2 — 2 Total retail 204 75 279 Interchange and other 47 1 48 Total revenue from contracts with customers 251 76 327 Alternative revenue and other 3 1 4 Total revenues $ 254 $ 77 $ 331

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Reconciliation between the statutory rate and effective tax rate: Three Months Ended March 31 2024 2023 Federal statutory rate 21.0 % 21.0 % State tax (net of federal tax effect) 6.2 6.2 (Decreases) increases: Plant regulatory differences (a) (4.3) (3.5) Other (net) 0.3 (1.3) Effective income tax rate 23.2 % 22.4 % (a)

Fair Value of Financial Asset_2

Fair Value of Financial Assets and Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Carrying Amount and Fair Value of Long-term Debt	March 31, 2024 Dec. 31, 2023 (Millions of Dollars) Carrying Amount Fair Value Carrying Amount Fair Value Long-term debt, including current portion $ 1,211 $ 1,104 $ 1,211 $ 1,117

Benefit Plans and Other Postr_2

Benefit Plans and Other Postretirement Benefits (Tables)	3 Months Ended
	Mar. 31, 2024
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost Three Months Ended March 31 2024 2023 (Millions of Dollars) Pension Benefits Service cost $ 1 $ 1 Interest cost (a) 2 2 Expected return on plan assets (a) (2) (2) Net periodic benefit cost $ 1 $ 1 (a) The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset. In January 2024, contributions totaling $100 million were made across Xcel Energy’s pension plans, of which $7 million was attributable to NSP-Wisconsin. Xcel Energy does not expect additional pension contributions during 2024.

Segment Reporting (Tables)

Segment Reporting (Tables)	3 Months Ended
	Mar. 31, 2024
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	NSP-Wisconsin's segment information: Three Months Ended March 31 (Millions of Dollars) 2024 2023 Regulated Electric Total revenues (a) $ 256 $ 254 Net income 33 33 Regulated Natural Gas Total revenues $ 54 $ 77 Net income 10 11 All Other Net income $ — $ 1 Consolidated Total Total revenues (a) $ 310 $ 331 Net income 43 45 (a) Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.

Selected Balance Sheet Data - A

Selected Balance Sheet Data - Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Accounts Receivable, Net
Accounts receivable	$ 98	$ 98
Less allowance for bad debts	(8)	(9)
Accounts receivable, net	$ 90	$ 89

Selected Balance Sheet Data - I

Selected Balance Sheet Data - Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventory [Line Items]
Total Inventories	$ 24	$ 29
Materials and supplies
Inventory [Line Items]
Inventories	12	11
Fuel
Inventory [Line Items]
Inventories	10	10
Natural gas
Inventory [Line Items]
Inventories	$ 2	$ 8

Selected Balance Sheet Data - P

Selected Balance Sheet Data - Property, Plant and Equipment (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 4,992	$ 4,877
Less accumulated depreciation	(1,660)	(1,640)
Property, plant and equipment, net	3,332	3,237
Electric plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,895	3,845
Natural gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	504	502
Common and other property
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	287	278
Construction work in progress
Public Utility, Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 306	$ 252

Borrowings and Other Financin_3

Borrowings and Other Financing Instruments, Commercial Paper (Details) - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Amount outstanding at period end		$ 0	$ 60,000,000
Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	[1]	150,000,000
Long-term Line of Credit		0	0
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		150,000,000	150,000,000
Amount outstanding at period end		0	60,000,000
Average amount outstanding		41,000,000	15,000,000
Maximum amount outstanding		$ 99,000,000	$ 93,000,000
Weighted average interest rate, computed on a daily basis		5.49%	4.85%
Weighted average interest rate at period end			5.50%
Money Pool
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 150,000,000	$ 150,000,000
Amount outstanding at period end		19,000,000	0
Average amount outstanding		12,000,000	6,000,000
Maximum amount outstanding		$ 54,000,000	$ 43,000,000
Weighted average interest rate, computed on a daily basis		5.33%	4.98%
Weighted average interest rate at period end		5.33%
[1] Expires in September 2027.

Borrowings and Other Financin_4

Borrowings and Other Financing Instruments, Letters of Credit (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Period	1 year
Amount outstanding at period end	$ 0	$ 60,000,000
Credit Facility
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 0	$ 0

Borrowings and Other Financin_5

Borrowings and Other Financing Instruments, Credit Facility (Details) - USD ($)		Mar. 31, 2024	Dec. 31, 2023
Payable to Affiliates
Line of Credit Facility [Line Items]
Notes Payable, Current		$ 0	$ 0
Credit Facility
Line of Credit Facility [Line Items]
Credit Facility	[1]	150,000,000
Outstanding	[2]	0
Available		150,000,000
Direct advances on the credit facility outstanding		$ 0	$ 0
[1] Expires in September 2027. Includes outstanding commercial paper.

Revenues (Details)

Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	$ 310	$ 331
Regulated Electric | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	256	254
Regulated Natural Gas | Total revenues
Disaggregation of Revenue [Line Items]
Total revenues	54	77
Retail
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	249	279
Retail | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	107	123
Retail | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	140	154
Retail | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2
Retail | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	197	204
Retail | Regulated Electric | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	77	82
Retail | Regulated Electric | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	118	120
Retail | Regulated Electric | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	2
Retail | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	52	75
Retail | Regulated Natural Gas | Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	30	41
Retail | Regulated Natural Gas | C&I
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	22	34
Retail | Regulated Natural Gas | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Interchange
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	57	48
Interchange | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	56	47
Interchange | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	1
Total revenue from contracts with customers
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	306	327
Total revenue from contracts with customers | Regulated Electric
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	253	251
Total revenue from contracts with customers | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	53	76
Alternative revenue and other
Disaggregation of Revenue [Line Items]
Alternative revenue and other	4	4
Alternative revenue and other | Regulated Electric
Disaggregation of Revenue [Line Items]
Alternative revenue and other	3	3
Alternative revenue and other | Regulated Natural Gas
Disaggregation of Revenue [Line Items]
Alternative revenue and other	$ 1	$ 1

Income Taxes (Details)

Income Taxes (Details)		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21%	21%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		6.20%	6.20%
Effective Income Tax Rate Reconciliation, Other Regulatory Items, Percent	[1]	(4.30%)	(3.50%)
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		0.30%	(1.30%)
Effective Income Tax Rate Reconciliation, Percent		23.20%	22.40%
[1]Plant regulatory differences primarily relate to the credit of excess deferred taxes to customers through the average rate assumption method. Income tax benefits associated with the credit are offset by corresponding revenue reductions.

Fair Value of Financial Asset_3

Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) $ in Millions	Mar. 31, 2024 USD ($)
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges	$ 0

Fair Value of Financial Asset_4

Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income (Details) - Other Derivative Instruments - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Natural Gas Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1	$ 2
Natural Gas Commodity [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities		$ 1

Fair Value of Financial Asset_5

Fair Value of Financial Assets and Liabilities - Fair Value of Long-Term Debt (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Carrying Amount	$ 1,211	$ 1,211
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt, Fair Value	$ 1,104	$ 1,117

Benefit Plans and Other Postr_3

Benefit Plans and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2024	Mar. 31, 2024	Mar. 31, 2023
Components of Net Periodic Benefit Cost [Abstract]
Service cost			$ 1	$ 1
Interest cost (a)	[1]		2	2
Expected return on plan assets (a)	[1]		(2)	(2)
Net periodic benefit cost			$ 1	$ 1
Contributions to pension plans		$ 7
Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 100
[1] The components of net periodic cost other than the service cost component are included in the line item “Other income (expense), net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.

Commitments and Contingencies G

Commitments and Contingencies Gas Trading Litigation (Details)	Mar. 31, 2024
Gas Trading Litigation
Loss Contingencies [Line Items]
Loss Contingency, Pending Claims, Number	1

Commitments and Contingencies (

Commitments and Contingencies (Details) - Enviromental Requirements $ in Millions	Mar. 31, 2024 USD ($)
Loss Contingencies [Line Items]
Cost of identified MGP, landfill, or disposal sites under current investigation and/or remediation	$ 13
Liability for estimated cost to comply with regulation	$ 5
Plants required for improvements	2
Other MGP, Landfill, or Disposal Sites [Domain]
Loss Contingencies [Line Items]
Number of identified MGP sites under current investigation and/or remediation	1

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Net income		$ 43	$ 45
Regulated and Unregulated Operating Revenue		310	331
Affiliate Revenue		53	50
Natural gas		54	77
Cost of identified MGP, landfill, or disposal sites under current investigation and/or remediation		13
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	310	331
Regulated Electric
Segment Reporting Information [Line Items]
Net income		33	33
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	[1]	256	254
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income		10	11
Revenues Including Intersegment Revenues		54	77
All Other
Segment Reporting Information [Line Items]
Net income		$ 0	$ 1
[1] Total revenues include $53 million and $50 million of affiliate electric revenue for the three months ended March 31, 2024 and 2023, respectively.