SOUTHWEST GAS CORP

We are restating our unaudited quarterly financial information for the second and third quarters of the year ended December 31, 2025 to correct (a) errors related to income tax expense and net deferred income tax liabilities and (b) an other immaterial error for the quarter ended September 30, 2025. The errors were identified by management in connection with the preparation of this Form 10-K- through our annual review control processes. These errors occurred following the Southwest Gas Holdings, Inc.’s sale of 13,207,142 shares of Centuri common stock on May 22, 2025, which resulted in income tax deconsolidation for Arizona, and subsequently following Southwest Gas Holdings, Inc.’s sale of 18,823,500 shares of Centuri common stock on August 11, 2025, which resulted in income tax deconsolidation for the remaining states, primarily California.

Evaluation of Disclosure Controls and Procedures

Management of Southwest Gas Holdings, Inc. and Southwest Gas has established disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), that are designed to provide reasonable assurance that information required to be disclosed in their respective reports filed or submitted under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms and to provide reasonable assurance that such information is accumulated and communicated to management of each company, including each respective Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosures.

Management, including our Chief Executive Officer and Chief Financial Officer, have conducted an evaluation of the effectiveness of our disclosure controls and procedures as of the end of the period covered by this report and, based on their evaluation, our Chief Executive Officer and Chief Financial Officer have concluded our disclosure controls and procedures were not effective at Southwest Gas Holdings, Inc. as of December 31, 2025 at attaining a reasonable assurance level, due to a material weakness in our internal control over financial reporting, as further described below.

In connection with our Quarterly Reports on Form 10-Q for the quarters ended June 30, 2025 and September 30, 2025, filed on August 6, 2025, and November 5, 2025, respectively, management evaluated the effectiveness of Southwest Gas Holdings, Inc.’s disclosure controls and procedures as of June 30, 2025 and September 30, 2025. Based upon those evaluations, our Chief Executive Officer and Chief Financial Officer concluded that Southwest Gas Holdings, Inc.'s disclosure controls and procedures were effective as of those dates. Subsequent to those evaluations our Chief Executive Officer and Chief Financial Officer re-evaluated the effectiveness of the Company’s disclosure controls and procedures and concluded that our disclosure controls and procedures were not effective as of June 30, 2025 and September 30, 2025, because of the material weakness described below.

Management nonetheless determined that the consolidated financial statements and related financial information of Southwest Gas Holdings included in this Form 10-K fairly present in all material respects our financial condition, results of operations and cash flows as of the dates presented, and for the periods ended on such dates, in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Management’s determination is based on a number of factors, including, but not limited to, management’s performance of extensive analysis and other post-closing procedures as of and for the year ended December 31, 2025.

Southwest Gas

Based on the most recent evaluation, as of December 31, 2025, the Chief Executive Officer and Chief Financial Officer, concluded Southwest Gas’ disclosure controls and procedures are effective at attaining the level of reasonable assurance noted above.

Management’s Reports on Internal Control Over Financial Reporting

Southwest Gas

Management of Southwest Gas is responsible for establishing and maintaining adequate internal control over financial reporting as defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. Under the supervision and with the participation of Southwest Gas management, including our Chief Executive Officer and Chief Financial Officer, an evaluation was conducted of the effectiveness of internal control over financial reporting based on the “Internal Control – Integrated Framework” (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based upon management’s evaluation under such framework, management concluded that Southwest Gas’ internal control over financial reporting was effective as of December 31, 2025. This annual report does not include a report of Southwest Gas’ registered public accounting firm regarding internal control over financial reporting pursuant to rules of the Securities and Exchange Commission that permit Southwest Gas to provide only this management’s report in this Form 10-K.

Management, including our Chief Executive Officer and Chief Financial Officer, of Southwest Gas Holdings, Inc. is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined by Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. Under the supervision and with the participation of Southwest Gas Holdings, Inc. management, including the Chief Executive Officer and Chief Financial Officer, an evaluation was conducted of the effectiveness of internal control over financial reporting based on the “Internal Control – Integrated Framework” (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based upon management’s evaluation under such framework, management concluded based upon the existence of the material weakness described below that internal control over financial reporting was not effective as of December 31, 2025.

A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of our annual or interim financial statements will not be prevented or detected on a timely basis.

The Company did not design and maintain an effective control to assess the impact on estimated future state apportionment rates upon a significant change in the business and structure in interim periods. This material weakness resulted in the misstatement of our income tax expense and net deferred income tax liabilities, and in the restatement of the Company's unaudited quarterly financial information as of and for the three and six months ended June 30, 2025, and the three and nine months ended September 30, 2025. The material weakness could result in additional errors of the aforementioned account balances or disclosures in the interim consolidated financial statements that would not be prevented or detected.

The effectiveness of the Company’s internal control over financial reporting as of December 31, 2025, has been audited by PricewaterhouseCoopers, LLP, an independent registered public accounting firm, as stated in their report which is included herein.

Remediation Plan

Management is committed to implementing changes to our internal control over financial reporting to ensure that the material weakness is remediated. We have evaluated the impact of the material weakness and will implement the following changes:

•We will expand our internal control framework over income tax accounting by modifying the control activities related to state tax apportionment rates. This expansion includes implementing a formal interim review control designed to identify, evaluate, and document the impact of any significant changes in the Company’s organizational or operational structure on apportionment methodologies and rates.

While we believe that this action will remediate the material weakness, we have not completed all of the corrective processes, procedures and related evaluation or remediation that we believe are necessary. As we continue to evaluate and work to remediate the material weakness, we may take additional measures to address the material weakness.

Until the remediation step set forth above, including the efforts to implement the necessary control activities we identify, are fully implemented and concluded to be operating effectively for a sufficient period of time, the material weakness described above will not be considered remediated.

Changes in Internal Control Over Financial Reporting

There have been no changes in Southwest Gas Holdings’ internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) during the fourth quarter of 2025 that have materially affected, or are likely to materially affect, the Company’s internal control over financial reporting.

There have been no changes in Southwest Gas Corporation’s internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) during the fourth quarter of 2025 that have materially affected, or are likely to materially affect Southwest Gas’ internal control over financial reporting.

Future changes in Internal Control Over Financial Reporting

During 2025, we initiated a project to implement a new financial statement consolidation software system. The implementation is expected to require modifications to certain business processes and internal controls over financial reporting and is anticipated to occur in mid-2026. Management is currently evaluating the design and operating effectiveness of internal controls related to the system implementation. The Audit Committee receives periodic updates on the status of the project and provides oversight consistent with its responsibilities for internal control over financial reporting. Any necessary changes to internal controls will be implemented prior to the applicable system reliance dates associated with the implementation.