Income Taxes	3 Months Ended
Mar. 31, 2020
Income Taxes
Income Taxes	10. Income Taxes Income tax expense was less than $0.1 million for the three months ended March 31, 2020 and 2019. Our effective tax rate differs from the statutory rate primarily as a result of state taxes, foreign taxes, nondeductible stock option expenses and changes in our valuation allowance. If all or a portion of our net operating loss carryforwards are subject to limitation because it is determined that we had previously experienced an “ownership change” as defined in section 382 of the Internal Revenue Code of 1986, as amended, our future cash flows could be adversely impacted due to increased tax liability. We reduce our deferred tax assets resulting from future tax benefits by a valuation allowance if, based on the weight of the available evidence, it is more likely than not that some portion or all of these deferred taxes will not be realized. The timing of the reversal of deferred tax liabilities associated with tax deductible goodwill is not certain and thus not available to assure the realization of a portion of the deferred tax assets. However, the reversal of deferred tax liabilities associated with tax deductible goodwill can be a source of taxable income to support the realization of a deductible temporary difference that is scheduled to reverse into net operating losses with an unlimited carryforward period. Except for the deferred tax liabilities resulting from tax deductible goodwill, we have deferred tax assets in excess of deferred tax liabilities before application of a valuation allowance for the periods presented. As we have insufficient history of generating income, the ultimate future realization of these excess deferred tax assets does not meet the more likely than not criteria and is thus subject to a valuation allowance. Accordingly, we have established a full valuation allowance against our deferred tax assets. We are subject to the accounting guidance for uncertain income tax positions. We believe it is more likely than not that our income tax positions and deductions will be sustained on audit and do not anticipate any adjustments which could result in a material adverse effect on our financial condition, results of operations, or cash flow. Our policy for recording interest and penalties associated with audits and uncertain tax positions is to record such items as a component of income tax expense, and no interest or penalties were recognized in the three months ended March 31, 2020 or 2019. There are no material uncertain tax positions and no uncertain income tax positions were recorded during the three months ended March 31, 2020 or 2019, and we do not expect our uncertain tax position to change materially during the next twelve months. We file tax returns in the United States, at both the federal and state level, and in several foreign jurisdictions. Due to net operating loss carryforwards, our tax returns are open to examination by the Internal Revenue Service and state jurisdictions for all years since inception.

10. Income Taxes

Income tax expense was less than $0.1 million for the three months ended March 31, 2020 and 2019.

Our effective tax rate differs from the statutory rate primarily as a result of state taxes, foreign taxes, nondeductible stock option expenses and changes in our valuation allowance. If all or a portion of our net operating loss carryforwards are subject to limitation because it is determined that we had previously experienced an “ownership change” as defined in section 382 of the Internal Revenue Code of 1986, as amended, our future cash flows could be adversely impacted due to increased tax liability.

We reduce our deferred tax assets resulting from future tax benefits by a valuation allowance if, based on the weight of the available evidence, it is more likely than not that some portion or all of these deferred taxes will not be realized. The timing of the reversal of deferred tax liabilities associated with tax deductible goodwill is not certain and thus not available to assure the realization of a portion of the deferred tax assets. However, the reversal of deferred tax liabilities associated with tax deductible goodwill can be a source of taxable income to support the realization of a deductible temporary difference that is scheduled to reverse into net operating losses with an unlimited carryforward period. Except for the deferred tax liabilities resulting from tax deductible goodwill, we have deferred tax assets in excess of deferred tax liabilities before application of a valuation allowance for the periods presented. As we have insufficient history of generating income, the ultimate future realization of these excess deferred tax assets does not meet the more likely than not criteria and is thus subject to a valuation allowance. Accordingly, we have established a full valuation allowance against our deferred tax assets.

We are subject to the accounting guidance for uncertain income tax positions. We believe it is more likely than not that our income tax positions and deductions will be sustained on audit and do not anticipate any adjustments which could result in a material adverse effect on our financial condition, results of operations, or cash flow.

Our policy for recording interest and penalties associated with audits and uncertain tax positions is to record such items as a component of income tax expense, and no interest or penalties were recognized in the three months ended March 31, 2020 or 2019. There are no material uncertain tax positions and no uncertain income tax positions were recorded during the three months ended March 31, 2020 or 2019, and we do not expect our uncertain tax position to change materially during the next twelve months.

We file tax returns in the United States, at both the federal and state level, and in several foreign jurisdictions. Due to net operating loss carryforwards, our tax returns are open to examination by the Internal Revenue Service and state jurisdictions for all years since inception.