Significant Accounting Policies and Responsibility for Financial Statements (Policies)	9 Months Ended
Sep. 30, 2026
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The Condensed Consolidated Financial Statements of each of TXNM, PNM, and TNMP include their accounts and those of subsidiaries in which that entity owns a majority voting interest. PNM also consolidates Valencia and ETBC I. See Note 6. PNM owns undivided interests in several jointly-owned power plants and records its pro-rata share of the assets, liabilities, and expenses for those plants. The agreements for the jointly-owned plants provide that if an owner were to default on its payment obligations, the non-defaulting owners would be responsible for their proportionate share of the obligations of the defaulting owner. In exchange, the non-defaulting owners would be entitled to their proportionate share of the generating capacity of the defaulting owner. There have been no such payment defaults under any of the agreements for the jointly-owned plants. PNMR Services Company expenses, which represent costs that are primarily driven by corporate level activities, are charged to the business segments. These services are billed at cost and are reflected as general and administrative expenses in the business segments. Other significant intercompany transactions between TXNM, PNM, and TNMP include interest and income tax sharing payments, as well as equity transactions. See Note 15. All intercompany transactions and balances have been eliminated.
New Accounting Pronouncements	New Accounting Pronouncements Information concerning recently issued accounting pronouncements that have not yet been adopted by the Company is presented below. The Company does not expect difficulty in adopting these standards by their required effective dates. Accounting Standards Update 2024-03 - Income Statement (Subtopic 220-40): Reporting Comprehensive Income - Expense Disaggregation Disclosures In November 2024, the FASB issued ASU 2024-03 that will require disclosure, in the notes to the financial statements, of specified information about certain costs and expenses at each interim and annual period. Disclosures should include amounts for purchases of inventory, employee compensation, depreciation, and intangible asset amortization; certain amounts that are already required to be disclosed under GAAP in the same disclosure as other disaggregation requirements; qualitative descriptions of the amounts remaining in relevant expense categories that are not disaggregated; and the total amount of selling expenses including the entity’s definition of selling expenses. In January 2025, ASU 2025-01 was issued to clarify that the amendments of ASU 2024-03 are effective for public business entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The Company is evaluating its current reporting capabilities and determining whether new reports may be necessary to comply with the disclosure requirements of the ASU. The Company expects to adopt the disclosure requirements of ASU 2024-03 with its Annual Report on Form 10-K for the year ending December 31, 2027. Accounting Standards Update 2025-06 – Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software In September 2025, the FASB issued ASU 2025-06 that updates the internal-use software guidance in subtopic 350-40 including the removal of all references to prescriptive and sequential developmental stages referred to as “project stages” throughout the subtopic. The new guidance requires an entity to start capitalizing software costs when management has authorized and committed to funding the project and it is probable that the project will be completed and used to perform the function it was intended for (referred to as the “probable-to-complete recognition threshold”). During the evaluation of the probable-to-complete recognition threshold, the entity is required to consider whether there is significant uncertainty associated with the development activities of the software. The amendments in this update are effective for all entities for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The amendments in this update permit an entity to apply the new guidance using a prospective transition approach, a modified transition approach (based on the status of a project and whether software costs were capitalized before the date of adoption), or a full retrospective transition approach. The Company has not yet determined which approach to adopt nor the impact that the new guidance will have on the accounting for its internal-use software projects. Accounting Standards Update 2025-10 – Government Grants (Topic 832): Accounting for Government Grants Received by Business Entities In December 2025, the FASB issued ASU 2025-10 to establish authoritative guidance for recognition, measurement, and presentation of government grants received by business entities. The new guidance defines a grant as a transfer of a monetary asset or a tangible non-monetary asset, other than in an exchange transaction, from a government to a business entity. The amendments in this ASU distinguish the accounting for grants between those that are conditioned on the purchase, construction, or acquisition of an asset (a grant related to an asset); and those that reimburse a business entity for operating expenses (a grant related to income). The guidance requires that a grant should not be recognized until: 1) it is probable that A) the business entity will comply with the conditions attached to the grant and B) that the grant will be received and 2) that the business entity meets the recognition guidance for a grant related to an asset or a grant related to income. The amendments in this update are effective for public business entities for annual reporting periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods. Early adoption is permitted. The amendments in this update permit an entity to apply the new guidance using a modified prospective approach to both grants that are entered into on or after the effective date or grants that are not complete as of the effective date; a modified retrospective approach to both grants that are entered into on or after the beginning of the earliest period presented or grants that are not complete as of the beginning of the earliest period presented (using a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented); or a full retrospective transition approach to all grants through a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented. The Company has not yet determined which approach to adopt nor the impact that the new guidance will have on the accounting for the government grants awarded. Accounting Standards Update 2025-11 – Interim reporting (Subtopic 270): Narrow-Scope Improvements In December 2025, the FASB issued ASU 2025-11 which clarifies and consolidates interim disclosure requirements. The ASU requires disclosure of material events occurring after the end of the last annual period and provides a comprehensive list of interim disclosures across multiple ASC Topics. The amendment is principle based and is modeled after previous SEC disclosure requirements, which is intended to help entities determine whether disclosures, not specified in Topic 270, should be provided in interim reporting periods. The amendment is effective for public business entities for interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is still evaluating the new standard. Accounting Standards Update 2026-02 - Environmental Credits and Environmental Credit Obligations (Topic 818) In May 2026, the FASB issued ASU 2026-02 which improves the financial accounting for and disclosure of environmental credits and environmental credit obligations. The ASU provides recognition, measurement, presentation, and disclosure requirements for all entities that generate, purchase, or receive environmental credits or have a regulatory compliance obligation that may be settled with environmental credits. The amendments in this update are effective for public business entities for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The Company is still evaluating the new standard.

In November 2024, the FASB issued ASU 2024-03 that will require disclosure, in the notes to the financial statements, of specified information about certain costs and expenses at each interim and annual period. Disclosures should include amounts for purchases of inventory, employee compensation, depreciation, and intangible asset amortization; certain amounts that are already required to be disclosed under GAAP in the same disclosure as other disaggregation requirements; qualitative descriptions of the amounts remaining in relevant expense categories that are not disaggregated; and the total amount of selling expenses including the entity’s definition of selling expenses. In January 2025, ASU 2025-01 was issued to clarify that the amendments of ASU 2024-03 are effective for public business entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The Company is evaluating its current reporting capabilities and determining whether new reports may be necessary to comply with the disclosure requirements of the ASU. The Company expects to adopt the disclosure requirements of ASU 2024-03 with its Annual Report on Form 10-K for the year ending December 31, 2027.

In September 2025, the FASB issued ASU 2025-06 that updates the internal-use software guidance in subtopic 350-40 including the removal of all references to prescriptive and sequential developmental stages referred to as “project stages” throughout the subtopic. The new guidance requires an entity to start capitalizing software costs when management has authorized and committed to funding the project and it is probable that the project will be completed and used to perform the function it was intended for (referred to as the “probable-to-complete recognition threshold”). During the evaluation of the probable-to-complete recognition threshold, the entity is required to consider whether there is significant uncertainty associated with the development activities of the software. The amendments in this update are effective for all entities for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The amendments in this update permit an entity to apply the new guidance using a prospective transition approach, a modified transition approach (based on the status of a project and whether software costs were capitalized before the date of adoption), or a full retrospective transition approach. The Company has not yet determined which approach to adopt nor the impact that the new guidance will have on the accounting for its internal-use software projects.

In December 2025, the FASB issued ASU 2025-10 to establish authoritative guidance for recognition, measurement, and presentation of government grants received by business entities. The new guidance defines a grant as a transfer of a monetary asset or a tangible non-monetary asset, other than in an exchange transaction, from a government to a business entity. The amendments in this ASU distinguish the accounting for grants between those that are conditioned on the purchase, construction, or acquisition of an asset (a grant related to an asset); and those that reimburse a business entity for operating expenses (a grant related to income). The guidance requires that a grant should not be recognized until: 1) it is probable that A) the business entity will comply with the conditions attached to the grant and B) that the grant will be received and 2) that the business entity meets the recognition guidance for a grant related to an asset or a grant related to income. The amendments in this update are effective for public business entities for annual reporting periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods. Early adoption is permitted. The amendments in this update permit an entity to apply the new guidance using a modified prospective approach to both grants that are entered into on or after the effective date or grants that are not complete as of the effective date; a modified retrospective approach to both grants that are entered into on or after the beginning of the earliest period presented or grants that are not complete as of the beginning of

the earliest period presented (using a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented); or a full retrospective transition approach to all grants through a cumulative-effect adjustment to the opening balance of retained earnings as of the earliest period presented. The Company has not yet determined which approach to adopt nor the impact that the new guidance will have on the accounting for the government grants awarded.

In December 2025, the FASB issued ASU 2025-11 which clarifies and consolidates interim disclosure requirements. The ASU requires disclosure of material events occurring after the end of the last annual period and provides a comprehensive list of interim disclosures across multiple ASC Topics. The amendment is principle based and is modeled after previous SEC disclosure requirements, which is intended to help entities determine whether disclosures, not specified in Topic 270, should be provided in interim reporting periods. The amendment is effective for public business entities for interim reporting periods beginning after December 15, 2027. Early adoption is permitted. The Company is still evaluating the new standard.

In May 2026, the FASB issued ASU 2026-02 which improves the financial accounting for and disclosure of environmental credits and environmental credit obligations. The ASU provides recognition, measurement, presentation, and disclosure requirements for all entities that generate, purchase, or receive environmental credits or have a regulatory compliance obligation that may be settled with environmental credits. The amendments in this update are effective for public business entities for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. The Company is still evaluating the new standard.