ONE Gas Inc

1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation - Our accompanying unaudited consolidated financial statements have been prepared pursuant to the rules and regulations of the SEC. These statements also have been prepared in accordance with GAAP and reflect all adjustments that, in our opinion, are necessary for a fair statement of the results for the interim periods presented. All such adjustments are of a normal recurring nature. The 2023 year-end consolidated balance sheet data was derived from audited consolidated financial statements but does not include all disclosures required by GAAP. These unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and footnotes in our Annual Report. Our significant accounting policies are described in Note 1 of our Notes to Consolidated Financial Statements in our Annual Report. The preparation of these financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts and disclosures in the financial statements. Although management believes these estimates are reasonable, actual results could differ materially from these estimates. Due to the seasonal nature of our business, the results of operations for the nine months ended September 30, 2024, are not necessarily indicative of the results that may be expected for a 12-month period.

Organization and Nature of Operations - We provide natural gas distribution services to approximately 2.3 million customers in Oklahoma, Kansas and Texas through our three divisions, Oklahoma Natural Gas, Kansas Gas Service and Texas Gas Service, respectively. We primarily serve residential, commercial and transportation customers in all three states.

Segments - We operate in one reportable business segment: regulated public utilities that deliver natural gas primarily to residential, commercial and transportation customers. Our accounting policies are the same as those described in Note 1 of the Notes to Consolidated Financial Statements in our Annual Report. We evaluate our financial performance principally on net income. For the three and nine months ended September 30, 2024 and 2023, we hadno single external customer from which we received 10 percent or more of our gross revenues.

Property, Plant and Equipment and Asset Removal Costs - Accounts payable for construction work in progress and asset removal costs decreased by approximately $15.8 million and $3.9 million for the nine months ended September 30, 2024 and 2023, respectively. Such amounts are not included in capital expenditures or asset removal costs in our consolidated statements of cash flows.

Accounts Receivable, Net - Accounts receivable represent valid claims against nonaffiliated customers for natural gas sold or services rendered. We assess the creditworthiness of our customers. Those customers who do not meet minimum standards may be required to provide security, including deposits and other forms of collateral, when appropriate and allowed by our tariffs. With approximately 2.3 million customers across three states, we are not exposed materially to a concentration of credit risk. We maintain an allowance for doubtful accounts based upon factors surrounding the credit risk of customers, historical trends, consideration of the current environment and other information. We recover natural gas costs related to accounts written off when they are deemed uncollectible through the purchased-gas cost adjustment mechanisms in each of our jurisdictions. At September 30, 2024 and December 31, 2023, our allowance for doubtful accounts was $12.9 million and $16.1 million, respectively.

Goodwill Impairment Test – We assess our goodwill for impairment at least annually on July 1, unless events or changes in circumstances indicate an impairment may have occurred before that time. As part of our goodwill impairment test, we may first assess qualitative factors (including macroeconomic conditions, industry and market considerations, cost factors and overall financial performance) to determine whether it is more likely than not that the fair value of our reporting unit is less than its carrying amount. If further testing is necessary or a quantitative test is elected to refresh our recurring qualitative assessments, we perform a quantitative impairment test for goodwill. We did not identify any impairment indicators for our goodwill and determined that no further testing was necessary.

Recently Issued Accounting Standards Update - In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures,” which is intended to enhance annual income tax disclosures to address investor requests for more information about the tax risks and opportunities present in an entity’s operations. The amendments in this standard require disclosure of additional information in specified categories with respect to the reconciliation of the effective tax rate to the statutory rate (the rate reconciliation) for federal, state, and foreign income taxes. They also require greater detail about individual reconciling items in the rate reconciliation to the extent the impact of those items exceeds a specified threshold. In addition to new disclosures associated with the rate reconciliation, the amendments in this update require information pertaining to taxes paid (net of refunds received) to be disaggregated for federal, state, and foreign taxes and further disaggregated for specific jurisdictions to the extent the related amounts exceed a quantitative threshold. The amendments in this update are effective for annual periods beginning after December 15, 2024, and early adoption is permitted. We are currently evaluating the impact of adopting this standard.

In November 2023, the FASB issued ASU 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures,” which is intended to improve annual and interim reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The amendments in this standard enhance interim disclosure requirements, clarify circumstances in which an entity can disclose multiple segment measures of profit or loss, provide new segment disclosure requirements for entities with a single reportable segment, and contain other disclosure requirements. The amendments in this update are effective for annual periods beginning after December 15, 2023, and interim periods within annual periods beginning after December 15, 2024. Early adoption is permitted. We are currently evaluating the impact of adopting this standard.

2. REVENUE

The following table sets forth our revenues disaggregated by source for the periods indicated:

Accrued unbilled natural gas sales revenues at September 30, 2024 and December 31, 2023, were $81.2 million and $191.4 million, respectively, and are included in accounts receivable on our consolidated balance sheets.

3. REGULATORY ASSETS AND LIABILITIES

The tables below present a summary of regulatory assets and liabilities, net of amortization, for the periods indicated:

Regulatory assets in our consolidated balance sheets, as authorized by various regulatory authorities, are probable of recovery. Base rates and certain riders are designed to provide a recovery of costs during the period such rates are in effect, but do not generally provide for a return on investment for amounts we have deferred as regulatory assets. All of our regulatory assets are subject to review by the respective regulatory authorities during future regulatory proceedings.

Winter weather event costs -At September 30, 2024, Texas Gas Service had deferred approximately $13.0 million in extraordinary costs associated with Winter Storm Uri attributable to its former West Texas service area. Pursuant to the approved settlement order, Texas Gas Service began collecting the extraordinary costs, including carrying costs, from those customers in January 2022.

The deferred winter weather event costs also include invoiced costs for natural gas purchases during Winter Storm Uri that have not been paid as we work with our suppliers for Kansas and Texas to resolve discrepancies in invoiced amounts. These amounts may be adjusted as the differences with suppliers are resolved. Settlements of these amounts are recoverable through the purchased gas cost mechanisms in the respective state. Future adjustments to the amounts are not expected to have a material impact on earnings.

GAAP does not provide comprehensive recognition and measurement guidance for many forms of government assistance received by business entities. Accordingly, we have accounted for the proceeds received from the TNG Corporation by analogy to International Accounting Standards No. 20, “Accounting for Government Grants and Disclosure of Government Assistance” consistent with a grant related to income. The proceeds received and the corresponding recognition of the deferred regulatory asset have been reflected in the cost of natural gas in our consolidated statements of income. As the proceeds reflect the recovery of our winter weather event regulatory asset, there was no material impact to earnings.

Other regulatory assets and liabilities - Purchased-gas costs represent the natural gas costs that have been over- or under-recovered from customers through the purchased-gas cost adjustment mechanisms, and includes natural gas utilized in our operations and premiums paid and any cash settlements received from our purchased natural gas call options.

The OCC, KCC and regulatory authorities in Texas have approved the recovery of pension costs and other postemployment benefits costs through rates for Oklahoma Natural Gas, Kansas Gas Service and Texas Gas Service, respectively. The costs recovered through rates are based on the net periodic benefit cost for defined benefit pension and other postemployment costs. Differences, if any, between the net periodic benefit cost, net of deferrals, and the amount recovered through rates are reflected in earnings. We historically have recovered defined benefit pension and other postemployment benefit costs through rates. We believe it is probable that regulators will continue to include the net periodic pension and other postemployment benefit costs in our cost of service.

We amortize reacquired debt costs in accordance with the accounting guidelines prescribed by the OCC and the KCC.

See Note 12 for additional information regarding our regulatory assets for MGP remediation costs.

Ad-valorem tax represents the difference in Kansas Gas Service’s taxes incurred each year above or below the amount approved in base rates. This difference is deferred as a regulatory asset or liability for a 12-month period. Kansas Gas Service then applies an adjustment to customers’ bills to refund the over-collected revenue or bill the under-collected revenue over the subsequent 12 months.

Weather normalization represents revenue over- or under-recovered through the WNA rider in Kansas. This amount is deferred as a regulatory asset or liability for a 12-month period. Kansas Gas Service then applies an adjustment to customers’ bills for 12 months to refund the over-collected revenue or bill the under-collected revenue.

The customer credit deferrals and the noncurrent regulatory liability for income tax rate changes represents deferral of the effects of enacted federal and state income tax rate changes on our ADIT and the effects of these changes on our rates. See Note 10 for additional information regarding the impact of income tax rate changes.

Recovery through rates resulted in amortization of regulatory assets of approximately $1.8 million and not material for the three months ended September 30, 2024 and 2023, respectively, and approximately $11.3 million and $11.1 million for the nine months ended September 30, 2024 and 2023, respectively.

4. CREDIT FACILITY AND SHORT-TERM DEBT

In October 2024, we entered into an agreement that increased the capacity of the ONE Gas Credit Agreement to $1.35 billion from $1.275 billion with commitments from existing lenders and the addition of a new lender. Other than the increased commitments and the addition of a new lender, all other terms and conditions of the ONE Gas Credit Agreement remain in full force and effect, including the maturity date of March 16, 2028.

The ONE Gas Credit Agreement provides for a $1.35 billion revolving unsecured credit facility and includes a $20 million letter of credit subfacility and a $60 million swingline subfacility. We can request an increase in commitments of up to an additional $150 million upon satisfaction of customary conditions, including receipt of commitments from either new lenders or increased commitments from existing lenders. The ONE Gas Credit Agreement is available to provide liquidity for working capital, capital expenditures, acquisitions and mergers, the issuance of letters of credit and for other general corporate purposes.

The ONE Gas Credit Agreement contains certain financial, operational and legal covenants. Among other things, these covenants include maintaining ONE Gas’ total debt-to-capital ratio of no more than 70 percent at the end of any calendar quarter. At September 30, 2024, our total debt-to-capital ratio was 54.5 percent and we were in compliance with all covenants under the ONE Gas Credit Agreement. Excluding the debt of KGSS-I, which is non-recourse to us, our total debt-to-capital ratio was 52.3 percent. We may reduce the unutilized portion of the ONE Gas Credit Agreement in whole or in part without premium or penalty. The ONE Gas Credit Agreement contains customary events of default. Upon the occurrence of certain events of default, our obligations under the ONE Gas Credit Agreement may be accelerated and the commitments may be terminated.

At September 30, 2024, we had $1.4 million in letters of credit issued andno borrowings under the ONE Gas Credit Agreement, with approximately $1.275 billion of remaining credit, which is available to repay our commercial paper borrowings.

In October 2024, we increased the capacity of our commercial paper program to $1.35 billion from $1.275 billion. Under our commercial paper program, we may issue unsecured commercial paper to fund short-term borrowing needs. The maturities of the commercial paper vary but may not exceed 270 days from the date of issue. Commercial paper is generally sold at par less a discount representing an interest factor. At September 30, 2024 and December 31, 2023, we had $951.4 million and $88.5 million of commercial paper outstanding with a weighted-average interest rate of 5.24 percent and 5.60 percent, respectively.

5. LONG-TERM DEBT

The table below presents a summary of our long-term debt outstanding for the periods indicated:

(a) Includes issuance costs and discounts for the KGSS-I Securitized Utility Tariff Bonds of $5.0 million and $5.3 million, at September 30, 2024 and December 31, 2023 respectively.

Senior Notes - The indenture governing our Senior Notes includes an event of default upon the acceleration of other indebtedness of $100 million or more. Such events of default would entitle the trustee or the holders of 25 percent in aggregate principal amount of the outstanding Senior Notes to declare those Senior Notes immediately due and payable in full.

Depending on the series, we may redeem our Senior Notes at par, plus accrued and unpaid interest to the redemption date, starting one month, three months or six months before their maturity dates. Prior to these dates, we may redeem these Senior Notes, in whole or in part, at a redemption price equal to the principal amount, plus accrued and unpaid interest and a make-whole premium. The redemption price will never be less than 100 percent of the principal amount of the respective Senior Note plus accrued and unpaid interest to the redemption date. Senior Notes are senior unsecured obligations, ranking equally in right of payment with all of our existing and future unsecured senior indebtedness.

In August 2024, we reopened our outstanding 5.10 percent senior notes due 2029 and issued an additional $250 million. After the completion of this offering, the aggregate principal amount of the outstanding 5.10 percent senior notes due 2029 is $550 million.

We repaid our $300 million of 3.61 percent senior notes due February 2024 and our $473 million of 1.10 percent senior notes due March 2024 upon maturity with commercial paper.

Securitized Utility Tariff Bonds - The KGSS-I Securitized Utility Tariff Bonds are governed by an indenture between KGSS-I and the indenture trustee. The indenture contains certain covenants that restrict KGSS-I’s ability to sell, transfer, convey, exchange, or otherwise dispose of its assets. KGSS-I’s assets cannot be used to settle ONE Gas’ obligations and the holders of the Securitized Utility Tariff Bonds have no recourse against ONE Gas. See Note 14 for additional discussion of the Kansas securitization transaction.

6. EQUITY

In February 2023, we entered into an at-the-market equity distribution agreement under which we may issue and sell shares of our common stock with an aggregate offering price up to $300 million. This at-the-market equity program replaced our previous at-the-market equity program, which began in February 2020, and expired in February 2023. Sales of common stock are made by means of ordinary brokers’ transactions on the NYSE, in block transactions or as otherwise agreed to between us and the sales agent. We are under no obligation to offer and sell common stock under the program. At September 30, 2024, we had $225.5 million of equity available for issuance under the program.

The following table summarizes all of our outstanding forward sale agreements at September 30, 2024:

Dividends Declared- In November 2024, we declared a dividend of $0.66 per share ($2.64 per share on an annualized basis) for shareholders of record as of November 19, 2024, payable on December 4, 2024.

7. ACCUMULATED OTHER COMPREHENSIVE LOSS

The following table sets forth the effect of reclassifications from accumulated other comprehensive loss in our consolidated statements of income for the periods indicated:

(a) These components of accumulated other comprehensive loss are included in the computation of net periodic benefit cost. See Note 9 for additional detail of our net periodic benefit cost.

(b) Regulatory adjustments represent pension and other postemployment benefit costs expected to be recovered through rates and are deferred as part of our regulatory assets. See Note 3 for additional disclosures of regulatory assets and liabilities.

8. EARNINGS PER SHARE

Basic EPS is calculated by dividing net income by the daily weighted-average number of common shares outstanding during the periods presented, which includes fully vested stock awards that have not yet been issued as common stock. Diluted EPS is based on shares outstanding for the calculation of basic EPS, plus unvested stock awards granted under our compensation plans and equity forward sale agreements, but only to the extent these instruments dilute earnings per share.

The following tables set forth the computation of basic and diluted EPS from continuing operations for the periods indicated:

9. EMPLOYEE BENEFIT PLANS

The following tables set forth the components of net periodic benefit cost for our pension and other postemployment benefit plans for the periods indicated:

We recover qualified pension benefit plan and other postemployment benefit plan costs through rates charged to our customers. Certain regulatory authorities require that the recovery of these costs be based on specific guidelines. The difference between these regulatory-based amounts and the periodic benefit cost calculated pursuant to GAAP is deferred as a regulatory asset or liability and amortized to expense over periods in which this difference will be recovered in rates, as authorized by the applicable regulatory authorities. For the nine months ended September 30, 2024 and 2023, regulatory deferrals related to net periodic benefit cost were $3.6 million and $4.2 million, respectively.

We capitalize all eligible service cost and non-service cost components under the accounting requirements of ASC Topic 980 (Regulated Operations) for rate-regulated entities. Capitalized non-service costs reflected as a regulatory asset in our consolidated balance sheets were $5.5 million at September 30, 2024, and $2.2 million at December 31, 2023. See Note 3 of the Notes to Consolidated Financial Statements in this Quarterly Report for additional information.

10. INCOME TAXES

We use an estimated annual effective tax rate for purposes of determining the income tax provision during interim reporting periods. In calculating our estimated annual effective tax rate, we consider forecasted annual pre-tax income and estimated permanent book versus tax differences, as well as tax credits. Adjustments to the effective tax rate and estimates will occur as information and assumptions change.

At September 30, 2024, we have no uncertain tax positions. Changes in tax laws or tax rates are recognized in the financial reporting period that includes the enactment date. We are no longer subject to income tax examination for years prior to 2019.

In 2024, the Internal Revenue Service issued Revenue Procedure 2024-15, which allows for the deferral of income taxes on securitization bond proceeds received from a qualifying state financing entity. In 2022, Oklahoma Natural Gas received $1.3 billion in securitization bond proceeds and reported this amount as income on its federal income tax return for that year. Following the new revenue procedure, we amended our 2022 federal tax return to request a refund of $55.5 million, pending review and approval by the Internal Revenue Service. Additionally, we plan to file an amended Oklahoma corporate income tax return in the fourth quarter of 2024 to request a state refund of $1.5 million. Consequently, as of September 30, 2024, we have recorded a receivable from the Internal Revenue Service to reflect the anticipated refund, along with a deferred tax liability to account for the future tax obligation.

Income tax expense reflects credits for the amortization of the regulatory liability associated with EDIT that was returned to customers of $1.5 million and $2.5 million for the three months ended September 30, 2024 and 2023, respectively, and $13.4 million and $15.5 million for the nine months ended September 30, 2024 and 2023, respectively.

11. OTHER INCOME AND OTHER EXPENSE

The following table sets forth the components of other income and other expense for the periods indicated:

12. COMMITMENTS AND CONTINGENCIES

Environmental Matters - We are subject to multiple laws and regulations regarding protection of the environment and natural and cultural resources, which affect many aspects of our present and future operations. Regulated activities include, but are not limited to, those involving air emissions, storm water and wastewater discharges, handling and disposal of solid and hazardous wastes, wetland preservation, plant and wildlife protection, hazardous materials use, storage and transportation, and pipeline and facility construction. These laws and regulations require us to obtain and/or comply with a wide variety of environmental clearances, registrations, licenses, permits and other approvals. Failure to comply with these laws, regulations, licenses and permits or the discovery of presently unknown environmental conditions may expose us to fines, penalties and/or interruptions in our operations that could be material to our results of operations. In addition, emission controls and/or other regulatory or permitting mandates under the CAA and other similar federal and state laws could require unexpected capital expenditures. We cannot assure that existing environmental statutes and regulations will not be revised or that new regulations will not be adopted or become applicable to us. Revised or additional statutes or regulations that result in increased compliance costs or additional operating restrictions could have a material adverse effect on our business, financial condition and results of operations. Our expenditures for environmental investigation and remediation compliance to-date have not been significant in relation to our financial position, results of operations or cash flows, and our expenditures related to environmental matters had no material effects on earnings or cash flows during the three and nine months ended September 30, 2024 and 2023.

We own or retain legal responsibility for certain environmental conditions at 12 former MGP sites in Kansas. These sites contain contaminants generally associated with MGP sites and are subject to control or remediation under various environmental laws and regulations. A consent agreement with the KDHE governs all environmental investigation and remediation work at these sites. The terms of the consent agreement require us to investigate these sites and set remediation activities based upon the results of the investigations and risk analysis. Remediation typically involves the management of contaminated soils and may involve removal of structures and monitoring and/or remediation of groundwater. We have completed or are addressing removal of the source of soil contamination at all 12 sites and continue to monitor groundwater atseven of the 12 sites according to plans approved by the KDHE. Regulatory closure has been achieved atfive of the 12 sites, but these sites remain subject to potential future requirements that may result in additional costs.

We have an AAO that allows Kansas Gas Service to defer and seek recovery of costs necessary for investigation and remediation at, and nearby, these 12 former MGP sites that are incurred after January 1, 2017, up to a cap of $15.0 million, net of any related insurance recoveries. Costs approved for recovery in a future rate proceeding would then be amortized over a 15- year period. The unamortized amounts will not be included in rate base or accumulate carrying charges. Following a determination that future investigation and remediation work approved by the KDHE exceeds $15.0 million, net of any related insurance recoveries, Kansas Gas Service will be required to file an application with the KCC for approval to increase the $15.0 million cap. In January 2024, we received $1.5 million in insurance proceeds for remediation costs related to these sites. At September 30, 2024 and December 31, 2023, we have deferred $30.4 million and $32.0 million, respectively, for accrued investigation and remediation costs pursuant to our AAO. Kansas Gas Service expects to file an application in the first quarter of 2025 for amounts deferred in excess of the cap.

We also own or retain legal responsibility for certain environmental conditions at a former MGP site in Texas. At the request of the TCEQ, we began investigating the level and extent of contamination associated with the site under their Texas Risk Reduction Program. A preliminary site investigation revealed that this site contains contaminants generally associated with MGP sites and is subject to control or remediation under various environmental laws and regulations. At September 30, 2024, estimated costs associated with expected remediation activities for this site are not material.

Our expenditures for environmental evaluation, mitigation, remediation and compliance to date have not been significant in relation to our financial position, results of operations or cash flows, and our expenditures related to environmental matters had no material effects on earnings or cash flows during the three and nine months ended September 30, 2024 and 2023. The reserve for remediation of our MGP sites was $13.6 million and $14.3 million at September 30, 2024 and December 31, 2023, respectively.

Pipeline Safety - We are subject to regulation under federal pipeline safety statutes and any analogous state regulations. These include safety requirements for the design, construction, operation, and maintenance of pipelines, including transmission and distribution pipelines. At the federal level, we are regulated by PHMSA. PHMSA regulations require the following for certain pipelines: inspection and maintenance plans; integrity management programs, including the determination of pipeline integrity risks and periodic assessments on certain pipeline segments; an operator qualification program, which includes certain trainings; a public awareness program that provides certain information; and a control room management plan.

As part of the Consolidated Appropriations Act, 2021, the PIPES Act reauthorized PHMSA through 2023 and directed the agency to move forward with several regulatory actions, including the “Pipeline Safety: Class Location Change Requirements” and the “Pipeline Safety: Safety of Gas Transmission and Gathering Pipelines” proposed rulemakings. Congress has also instructed PHMSA to issue final regulations that will require operators of new and existing transmission and distribution pipeline facilities to conduct certain leak detection and repair programs and to require facility inspection and maintenance plans to align with those regulations. To the extent such rulemakings impose more stringent requirements on our facilities, we may be required to incur expenditures that may be material.

Legal Proceedings - We are a party to various litigation matters and claims that have arisen in the normal course of our operations. While the results of litigation and claims cannot be predicted with certainty, we believe the reasonably possible losses from such matters, individually and in the aggregate, are not material. Additionally, we believe the probable outcome of such matters will not have a material adverse effect on our results of operations, financial position or cash flows.

13. DERIVATIVE FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS

Accounting Treatment - We record all derivative instruments at fair value, with the exception of normal purchases and normal sales that are expected to result in physical delivery. The accounting for changes in the fair value of a derivative instrument depends on whether it has been designated and qualifies as part of a hedging relationship and, if so, the reason for holding it, or if regulatory requirements impose a different accounting treatment.

If certain conditions are met, we may elect to designate a derivative instrument as a hedge of exposure to changes in fair values or cash flows. We have not elected to designate any of our derivative instruments as hedges.

The table below summarizes the various ways in which we account for our derivative instruments and the impact on our consolidated financial statements:

Fair Value Measurements - We define fair value as the price that would be received from the sale of an asset or the transfer of a liability in an orderly transaction between market participants at the measurement date. We use the market and income approaches to determine the fair value of our assets and liabilities and consider the markets in which the transactions are executed. We measure the fair value of a group of financial assets and liabilities consistent with how a market participant would price the net risk exposure at the measurement date.

Fair Value Hierarchy - At each balance sheet date, we utilize a fair value hierarchy to classify fair value amounts recognized or disclosed in our consolidated financial statements based on the observability of inputs used to estimate such fair value. The levels of the hierarchy are described below:

•Level 1 - Unadjusted quoted prices in active markets for identical assets or liabilities;

•Level 2 - Significant observable pricing inputs other than quoted prices included within Level 1 that are, either directly or indirectly, observable as of the reporting date. Essentially, this represents inputs that are derived principally from or corroborated by observable market data; and

•Level 3 - May include one or more unobservable inputs that are significant in establishing a fair value estimate. These unobservable inputs are developed based on the best information available and may include our own internal data.

We recognize transfers into and out of the levels as of the end of each reporting period.

Determining the appropriate classification of our fair value measurements within the fair value hierarchy requires management’s judgment regarding the degree to which market data is observable or corroborated by observable market data. We categorize derivatives for which fair value is determined using multiple inputs within a single level, based on the lowest level input that is significant to the fair value measurement in its entirety.

Derivative Instruments - Our derivatives are comprised of over-the-counter natural gas fixed price swaps and call options.

Swaps -At September 30, 2024, we held over-the-counter natural gas fixed-price swaps for the heating season ending March 2025, with a total notional amount of 9.45 Bcf. At December 31, 2023, we held over-the counter natural gas fixed-prices swaps for the heating season ending March 2024 with a total notional amount of 5.1 Bcf.

Options - At September 30, 2024, we held natural gas call options for the heating season ending March 2025, with the total notional amounts of 1.02 Bcf, for which we paid premiums of $1.0 million. At December 31, 2023, we held purchased natural gas call options for the heating season ended March 2024, with total notional amounts of 0.5 Bcf, for which the premiums paid and the fair value were not material.

We have not designated any of our derivative instruments as accounting hedges. These contracts are included in, and recoverable through, our purchased-gas cost adjustment mechanisms. Additionally, premiums paid, changes in fair value and any settlements received associated with these contracts are deferred as part of our unrecovered purchased-gas costs in our consolidated balance sheets. There wereno transfers between levels for the periods presented.

Other Financial Instruments - The approximate fair value of cash and cash equivalents, restricted cash and cash equivalents, accounts receivable and accounts payable is equal to book value, due to the short-term nature of these items. Commercial paper is due upon demand and, therefore, the carrying amounts approximate fair value.

The following tables summarize, by level within the fair value hierarchy, our derivative and other assets and liabilities that were accounted for at fair value on a recurring basis at September 30, 2024 and December 31, 2023:

(a) The fair value is included in other current assets and other current liabilities in our consolidated balance sheets.

(b) The fair value is included in other current and noncurrent assets and other current and noncurrent liabilities in our consolidated balance sheets.

(c) Our over-the-counter natural gas fixed-price swaps are presented on a net basis when the right of offset exists.

(a) The fair value is included in other current assets and other current liabilities in our consolidated balance sheets.

(b) The fair value is included in other current and noncurrent assets and other current and noncurrent liabilities in our consolidated balance sheets.

The estimated fair value of our long-term debt, including current maturities, was $2.4 billion and $2.8 billion at September 30, 2024 and December 31, 2023, respectively. The estimated fair value of our long-term debt was determined using quoted market prices, and is classified as Level 2.

14. VARIABLE INTEREST ENTITY

KGSS-I is a special-purpose, wholly owned subsidiary of ONE Gas that was formed for the purpose of issuing securitized bonds to recover extraordinary costs incurred by Kansas Gas Service resulting from Winter Storm Uri. KGSS-I’s assets cannot be used to settle ONE Gas’ obligations and the holders of the Securitized Utility Tariff Bonds have no recourse against ONE Gas. See Note 5 for additional information about the securitization financing.

KGSS-I is considered to be a variable interest entity. As a result, KGSS-I is included in the consolidated financial statements of ONE Gas. No gain or loss was recognized upon initial consolidation.

The following table summarizes the impact of KGSS-I on our consolidated balance sheets, for the periods indicated:

The following table summarizes the impact of KGSS-I on our consolidated statements of income, for the periods indicated: