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Income Taxes | 6 Months Ended
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Mar. 31, 2025
Income Tax Disclosure [Abstract] |
Income Taxes | Income Taxes Income Tax Expense Our interim effective tax rates reflect the estimated annual effective tax rates for the fiscal years ended September 30, 2025 and 2024, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended March 31, 2025 and 2024 were 19.5% and 15.7% and for the six months ended March 31, 2025 and 2024 were 19.0% and 15.3%. These effective tax rates differ from the federal statutory tax rate of 21% primarily due to the amortization of excess deferred federal income tax liabilities, tax credits, state income taxes, and other permanent book-to-tax differences. These adjustments have a relative impact on the effective tax rate proportionally to pretax income or loss. Regulatory Excess Deferred Taxes Regulatory excess net deferred taxes represent changes in our net deferred tax liability related to our cost of service ratemaking due to the enactment of the Tax Cuts and Jobs Act of 2017 (the TCJA), a Kansas legislative change enacted in fiscal 2020, and a Louisiana legislative change enacted in fiscal 2025. Currently, the regulatory excess net deferred tax liability of $178.6 million is being returned over various periods. Of this amount, $115.5 million is being returned to customers over 12 - 60 months. An additional $48.6 million is being returned to customers on a provisional basis over 15 - 68 years until our regulators establish the final refund periods. The refund of the remaining $14.5 million will be addressed in future rate proceedings. As of March 31, 2025 and September 30, 2024, $73.9 million and $79.7 million is recorded in other current liabilities.

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