Income Taxes

6 Months Ended

Mar. 31, 2024

Income Tax Disclosure [Abstract]

Income Taxes

10. Income Taxes

For interim income tax reporting, the Company estimates its full-year effective tax rate and applies it to fiscal year-to-date pretax income (loss), excluding unusual or infrequently occurring discrete items. Tax jurisdictions with losses for which tax benefits cannot be realized are excluded. The Company reported income tax benefit of $0.1 million and income tax expense of $(0.4) million for the three months ended March 31, 2024 and 2023, respectively, and income tax benefit of $0.0 million and income tax expense of $(0.2) million for the six months ended March 31, 2024 and 2023, respectively.

•Beginning in our fiscal 2023, certain research and development (“R&D”) costs are required to be capitalized and amortized over a five-year period under the Tax Cuts and Jobs Act enacted in December 2017. This change impacts the expected U.S. federal and state income tax expense and cash taxes paid and to be paid for our fiscal 2024 and 2023.

•Since September 30, 2022, we have maintained a full valuation allowance against U.S. net deferred tax assets. As a result, we are no longer recording a tax benefit associated with U.S. pretax losses and incremental deferred tax assets.

•Recurring items cause our effective tax rate to differ from the U.S. federal statutory rate of 21%, including foreign-derived intangible income (“FDII”) deductions in the U.S., U.S. federal and Irish R&D credits, Irish and U.S. state tax rates, and excess tax benefits associated with stock-based compensation.

A valuation allowance is required to be recognized against deferred tax assets if, based on the available evidence, it is more likely than not (defined as a likelihood of more than 50%) that all or a portion of such assets will not be realized. We apply judgment to consider the relative impact of negative and positive evidence, and the weight given to negative and positive evidence is commensurate with the extent to which such evidence can be objectively verified. Objective historical evidence, such as cumulative three-year pre-tax losses adjusted for permanent adjustments, is given greater weight than subjective positive evidence, such as forecasts of future earnings. The more objective negative evidence that exists limits our ability to consider other, potentially positive, subjective evidence, such as our future earnings projections. Based on our evaluation of all available positive and negative evidence, and by placing greater weight on the objectively verifiable evidence, we determined, as of March 31, 2024 and September 30, 2023, that it is more likely than not that our net U.S. deferred tax assets will not be realized. Due to significant estimates used to establish the valuation allowance and the potential for changes in facts and circumstances, it is reasonably possible that we will be required to record additional adjustments to the valuation allowance in future reporting periods that could have a material effect on our results of operations.

Discrete tax benefits related to stock-based compensation awards vested, expired, canceled and exercised was $0.1 million or less for each of the three months ended December 31, 2023 and 2022 and $0.1 million or less for each of the six months ended March 31, 2024 and 2023. The total amount of unrecognized tax benefits, excluding interest and penalties that, if recognized, would affect the effective tax rate was $3.6 million and $3.1 million as of March 31, 2024 and September 30, 2023, respectively. Interest and penalties related to unrecognized tax benefits are recorded in income tax benefit (expense).

The Company files income tax returns, including returns for its subsidiaries, in the U.S. federal jurisdiction and in various state jurisdictions, as well as several non-U.S. jurisdictions. Uncertain tax positions are related to tax years that remain subject to examination. The Internal Revenue Service commenced an examination of the Company’s fiscal 2019 U.S. federal tax return in fiscal 2022; the examination has not been completed. U.S. federal income tax returns for years prior to fiscal 2019 are no longer subject to examination by federal tax authorities. For tax returns for U.S. state and local jurisdictions, the Company is no longer subject to examination for tax years generally before fiscal 2013. For tax returns for non-U.S. jurisdictions, the Company is no longer subject to income tax examination for years prior to 2019. There were no undistributed earnings in foreign subsidiaries as of March 31, 2024 and September 30, 2023.