Income Taxes

6 Months Ended

Mar. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

Effective Tax Rate

The effective income tax rate was 6.7% and 16.5% during the quarters ended March 31, 2020 and 2019, respectively, and (8.5)% and 4.9% during the six months ended March 31, 2020 and 2019, respectively. The provision for income taxes during interim quarterly reporting periods is based on our estimates of the effective tax rates for the full fiscal year. The effective tax rate in any quarter can also be affected positively or negatively by adjustments that are required to be reported in the specific quarter of resolution.

The effective tax rates for the six months ended March 31, 2020 and 2019 were both impacted by the recording of excess tax benefits relating to stock awards that vested in December of both years. In addition, stock exercises during the quarter ended March 31, 2020 resulted in an additional increase in excess tax benefits.

The total unrecognized tax benefit for uncertain tax positions is estimated to be $7.1 million and $5.8 million at March 31, 2020 and September 30, 2019, respectively. We recognize interest expense related to unrecognized tax benefits and penalties as part of the provision for income taxes in our condensed consolidated statements of income and comprehensive income. We have accrued interest of $0.5 million and $0.3 million related to unrecognized tax benefits as of March 31, 2020 and September 30, 2019, respectively.