Income taxes	6 Months Ended
Jun. 30, 2019
Income taxes	14. Income taxes For the three and six months ended June 30, 2019, we recorded income tax expense of approximately $3.4 million and $5.1 million, respectively. For the three and six months ended June 30, 2018, we recorded income tax expense of approximately $1.6 million and $2.4 million, respectively. The change in tax expense for the three and six months ended June 30, 2019 was primarily driven by the difference in projected annual operating income or loss compared to our actual results as well as the recognition of certain discrete items in the current period. As of June 30, 2019, a full valuation allowance continues to be recorded against our U.S. and Swiss net deferred tax assets. This position is based on an analysis of positive and negative evidence, including analyzing three-year cumulative pre-tax income or loss, projections of future taxable income as well as other quantitative and qualitative information. The balance of our unrecognized tax benefits (including penalties and interest) increased by approximately $0.9 million during the six months ended June 30, 2019, of which only $0.2 million was recorded as an increase to noncurrent other liabilities on the condensed consolidated balance sheet. The increase is primarily driven by unrecognized tax benefits related to current year operations and research and development tax credits.

Income taxes

6 Months Ended

Jun. 30, 2019

14. Income taxes

For the three and six months ended June 30, 2019, we recorded income tax expense of approximately $3.4 million and $5.1 million, respectively. For the three and six months ended June 30, 2018, we recorded income tax expense of approximately $1.6 million and $2.4 million, respectively. The change in tax expense for the three and six months ended June 30, 2019 was primarily driven by the difference in projected annual operating income or loss compared to our actual results as well as the recognition of certain discrete items in the current period.

As of June 30, 2019, a full valuation allowance continues to be recorded against our U.S. and Swiss net deferred tax assets. This position is based on an analysis of positive and negative evidence, including analyzing three-year cumulative pre-tax income or loss, projections of future taxable income as well as other quantitative and qualitative information.

The balance of our unrecognized tax benefits (including penalties and interest) increased by approximately $0.9 million during the six months ended June 30, 2019, of which only $0.2 million was recorded as an increase to noncurrent other liabilities on the condensed consolidated balance sheet. The increase is primarily driven by unrecognized tax benefits related to current year operations and research and development tax credits.