|9 Months Ended|
Sep. 30, 2021
|Income Tax Disclosure [Abstract]|
|Income Taxes||Income Taxes
Our tax provision for interim periods is determined using an estimated annual effective tax rate, adjusted for discrete events arising in each respective quarter. During each interim period, we update the estimated annual effective tax rate which is subject to significant volatility due to several factors, including our ability to accurately predict the income (loss) before provision for income taxes in multiple jurisdictions, the effects of acquisitions, the integration of those acquisitions, and changes in tax law. In circumstances where we are unable to predict income (loss) in multiple jurisdictions, the actual year to date effective tax rate may be the best estimate of the annual effective tax rate for purposes of determining the interim provision for income tax.
We recorded income tax expense of $1.9 million and $4.3 million for the three and nine months ended September 30, 2021, respectively. The effective tax rate was 25.7% and 27.3% for the three and nine months ended September 30, 2021, respectively. We recorded a benefit from income tax of $1.6 million and $6.6 million for the three and nine months ended September 30, 2020, respectively. The effective tax rate was 14.4% and 23.2% for the three and nine months ended September 30, 2020, respectively. The increase in the effective tax rate for the three months ended September 30, 2021 compared with the three months ended September 30, 2020, is primarily attributable to changes in distribution of income and loss among jurisdictions with varying tax rates. Other significant factors impacting the current period effective tax rate included Federal and California research and development credits, non-deductible executive compensation expenses, and other discrete events.
We recorded no change related to unrecognized tax benefits for the three months ended September 30, 2021. Within the next twelve months, it is possible that the uncertain tax positions may change with a range of approximately zero to $0.2 million. Our tax returns remain open to examination as follows: U.S Federal, 2017 through 2020, U.S. states, 2016 through 2020, and significant foreign jurisdictions, generally 2016 through 2020.
The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.
Reference 1: http://www.xbrl.org/2003/role/disclosureRef