Income Taxes	3 Months Ended
Mar. 31, 2019
Income Taxes
Income Taxes	11. Income Taxes Income tax benefit was $0.8 million for the three months ended March 31, 2019, compared to $0.1 million for the three months ended March 31, 2018, or approximately 28% and 14% of income (loss) before income taxes, respectively. The effective tax rate for the three months ended March 31, 2019 differs from the U.S. federal statutory rate of 21% primarily due to the limitations on tax deductions allowable for executive compensation and global intangible low-taxed income, or GILTI, state income taxes, and foreign income taxes; offset by tax deductions resulting from stock-based compensation. As of December 31, 2018, the Company’s NOL carryforward amounts for U.S. federal income and state tax purposes were $57.1 million and $61.1 million, respectively. The federal and state NOL carryforwards will expire between 2020 and 2037 if not utilized. In addition to the NOL carryforwards, as of December 31, 2018, the Company had U.S. federal and state research and development credit carryforwards of $6.4 million and $2.8 million, respectively, which will expire between 2019 and 2034. The Company files income tax returns in the United States, including various state and local jurisdictions. The Company’s subsidiaries file income tax returns in Australia, China, Germany, India, New Zealand, Serbia, Switzerland, and the United Kingdom. The Company is subject to federal income tax as well as income tax of multiple state and foreign jurisdictions. The Company is no longer subject to income tax examinations for the following jurisdictions and years: federal, for years before 2015; state and local, for years before 2014; or foreign, for years before 2013. However, federal net operating loss and credit carryforwards from all years are subject to examination and adjustments for at least three years following the year in which the attributes are used.

11. Income Taxes

Income tax benefit was $0.8 million for the three months ended March 31, 2019, compared to $0.1 million for the three months ended March 31, 2018, or approximately 28% and 14% of income (loss) before income taxes, respectively. The effective tax rate for the three months ended March 31, 2019 differs from the U.S. federal statutory rate of 21% primarily due to the limitations on tax deductions allowable for executive compensation and global intangible low-taxed income, or GILTI, state income taxes, and foreign income taxes; offset by tax deductions resulting from stock-based compensation.

As of December 31, 2018, the Company’s NOL carryforward amounts for U.S. federal income and state tax purposes were $57.1 million and $61.1 million, respectively. The federal and state NOL carryforwards will expire between 2020 and 2037 if not utilized. In addition to the NOL carryforwards, as of December 31, 2018, the Company had U.S. federal and state research and development credit carryforwards of $6.4 million and $2.8 million, respectively, which will expire between 2019 and 2034.

The Company files income tax returns in the United States, including various state and local jurisdictions. The Company’s subsidiaries file income tax returns in Australia, China, Germany, India, New Zealand, Serbia, Switzerland, and the United Kingdom. The Company is subject to federal income tax as well as income tax of multiple state and foreign jurisdictions. The Company is no longer subject to income tax examinations for the following jurisdictions and years: federal, for years before 2015; state and local, for years before 2014; or foreign, for years before 2013. However, federal net operating loss and credit carryforwards from all years are subject to examination and adjustments for at least three years following the year in which the attributes are used.