Income Taxes

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

6. Income Taxes

We generally calculate income taxes in interim periods by applying an estimated annual effective income tax rate to income or loss before income taxes and by calculating the tax effect of discrete items recognized during such periods. Our estimated annual effective income tax rate is based on our estimated full year income or loss and the related income taxes for each jurisdiction in which we operate. This rate can be affected by estimates of full year pre-tax income or loss and permanent differences.

The effective income tax rate was 11.8% and 115.3% for the three months ended March 31, 2022 and 2021, respectively. The primary differences between our effective income tax rates and the federal statutory tax rate for the three months ended March 31, 2022 and 2021 were due to the effects of non-deductible officers’ stock-based compensation expense, state income taxes, benefits from research and development tax credits and excess tax benefits from our equity awards. The effective income tax rate for the three months ended March 31, 2022 was further impacted by the valuation allowance on our net deferred tax assets.

We consider all available evidence, both positive and negative in assessing the extent to which a valuation allowance should be applied against our net deferred tax assets. Due principally to cumulative three-year pre-tax losses adjusted for permanent adjustments, primarily from substantial excess tax benefits realized from the exercise of stock options granted prior to our initial public offering ("IPO"), and a significant number of outstanding stock options granted prior to our IPO that are or will be available to be exercised in future tax periods which may generate incremental excess tax benefits if they are exercised, we maintain a full valuation allowance against our net deferred tax assets in excess of tax amortizable goodwill as of March 31, 2022.

Our judgment regarding the need of a valuation allowance may reasonably change in the next twelve months. The exact timing and amount of any release of the valuation allowance is subject to change depending on the level of tax profitability that we achieve, changes in tax laws or regulations, and exercises of outstanding stock options granted prior to our IPO in future periods.

As of December 31, 2021, we had unrecognized tax benefits of $14.8 million, of which approximately $5.1 million of unrecognized tax benefits, if recognized, would impact the effective income tax rate. The remaining $9.7 million of unrecognized tax benefits would not impact the effective income tax rate to the extent that we continue to maintain a full valuation allowance against our net deferred tax assets. There were no significant changes to our unrecognized tax benefits during the three months ended March 31, 2022, and we do not expect to have any significant changes to unrecognized tax benefits through the end of 2022.