Impact of New Accounting Standards and Interpretations

12 Months Ended

Sep. 30, 2025

Accounting Changes and Error Corrections [Abstract]

Accounting Standards Update and Change in Accounting Principle [Text Block]

Impact of New Accounting Standards and Interpretations

The following are accounting standard updates issued by the Financial Accounting Standards Board ("FASB") that TVA adopted during 2025:

Improvements to Reportable Segment Disclosures
Description	This guidance improves reportable segment disclosure requirements, primarily through enhanced disclosures about significant segment expenses. The amendments require a public entity to disclose, on an annual and interim basis, significant segment expenses that are regularly provided to the Chief Operating Decision Maker ("CODM") and included within each reported measure of segment profit and loss. It also requires a public entity that has a single reportable segment to provide all of the disclosures required by the amendments and all existing segment disclosures. The amendments are effective for public entities for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Upon adoption, a public entity should apply the amendments retrospectively to all prior periods presented in the financial statements.
Effective Date for TVA	TVA adopted the guidance on September 30, 2025, and applied it retrospectively.
Effect on the Financial Statements or Other Significant Matters	The adoption of this standard resulted in expanded disclosures of significant segment expenses and enhanced qualitative information about the CODM's title and the use of net income as the segment profit measure. See Note 25 — Segment Reporting for further details.

Measurement of Credit Losses for Accounts Receivable and Contract Assets
Description	The amended guidance simplifies the estimation of credit losses on current accounts receivable and current contract assets arising from transactions accounted for under the accounting guidance for Revenue from Contracts with Customers. The amendments allow all entities to elect a practical expedient to assume that the current conditions as of the balance sheet date will remain unchanged for the remaining life of the asset when developing a reasonable and supportable forecast as part of estimating expected credit losses on these assets.
Effective Date for TVA	This new standard is effective for TVA’s interim and annual reporting periods beginning October 1, 2026. Early adoption is permitted, and TVA adopted this standard on September 30, 2025, on a prospective basis.
Effect on the Financial Statements or Other Significant Matters	Adoption of this standard did not have a material impact on TVA’s financial condition, results of operations, or cash flows.

The following accounting standards or rules have been issued but as of September 30, 2025, were not effective and had not been adopted by TVA:

Enhancement and Standardization of Climate-Related Disclosures for Investors
Description	In March 2024, the Securities and Exchange Commission ("SEC") adopted its climate-related final rule (SEC Release No. 34-99678, The Enhancement and Standardization of Climate-Related Disclosures for Investors). In April 2024, the SEC voluntarily stayed the new rule as a result of pending legal challenges, in March 2025, the SEC withdrew its legal defense of the rule, and in April 2025, the United States Court of Appeals for the Eighth Circuit suspended the litigation over the validity of the rule. The new rule, if implemented as adopted, will require registrants to provide certain climate-related information in their annual reports and registration statements and will also require the dollar impact of severe weather events and other natural conditions, as well as amounts related to carbon offsets and renewable energy credits or certificates, to be disclosed in the audited financial statements in certain circumstances. If the new rule is implemented as adopted, the disclosure requirements will begin phasing in for fiscal years beginning on or after January 1, 2027 for non-accelerated filers.
Effective Date for TVA	Fiscal year beginning October 1, 2027.
Effect on the Financial Statements or Other Significant Matters	TVA is currently evaluating the impact of the rule on its disclosures.

Disaggregation of Income Statement Expenses
Description	This guidance improves the disclosures about a public entity's expenses in the notes to the financial statements and requires disclosure of specified information about certain costs and expenses. The amendments require a public entity to disclose, on an annual and interim basis, purchases of inventory, employee compensation, depreciation, intangible asset amortization, and depletion for each income statement line item that contains those expenses. Specified expenses, gains, or losses that are already disclosed under existing U.S. GAAP are required to be included in the disaggregated income statement expense line item disclosures, and any relevant remaining amounts need to be described qualitatively. Separate disclosures of total selling expenses and an entity’s definition of those expenses are also required. The amendments are effective for public entities for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Upon adoption, a public entity can apply the amendments prospectively or apply them retrospectively to all prior periods presented in the financial statements.
Effective Date for TVA	Fiscal year beginning October 1, 2027, and interim periods beginning October 1, 2028.
Effect on the Financial Statements or Other Significant Matters	The adoption of this standard will result in TVA including the additional required disclosures, and TVA does not expect an impact on its financial condition, results of operations, or cash flows.

Accounting and Disclosure of Costs Related to Internally Developed Software
Description	This guidance amends the accounting for and disclosure of costs related to internally developed software, eliminating project stages, clarifying significant development uncertainty by requiring costs to be recognized only when uncertainty is resolved, and aligning capitalization rules with those for externally sold software. Key changes include the elimination of distinct project stages for development, a redefined meaning of probable as likely, and requirements to assess significant development uncertainty for all software projects to determine when to capitalize costs. In addition, the guidance specifies that the property, plant, and equipment disclosure requirements shall be applied to all capitalized software costs. The amendments are effective for all public entities for fiscal years beginning after December 15, 2027, and interim periods within those fiscal years. Upon adoption, a public entity may apply the guidance using a prospective, retrospective, or modified transition approach.
Effective Date for TVA	The new standard is effective for TVA's interim and annual reporting periods beginning October 1, 2028.
Effect on the Financial Statements or Other Significant Matters	The adoption of this standard is not expected to have a material impact on TVA’s financial condition, results of operations, cash flows, or disclosures.