13. Income Taxes

Our effective tax rates for the periods presented were as follows:

Six Months Ended

October 27,

2017

October 28,

2016

Effective tax rates

17.7

26.1

Our effective tax rates reflect the impact of a significant amount of our earnings, primarily income from our European operations which are headquartered in the Netherlands, being taxed in foreign jurisdictions at rates below the U.S. statutory tax rate. The differences in effective tax rates for the six months ended October 27, 2017 and October 28, 2016 were primarily a result of differences in discrete impacts related to stock-based compensation and differences in year-to-date profits before tax.

As of October 27, 2017, we had $222 million of gross unrecognized tax benefits, of which $157 million has been recorded in other long-term liabilities. Unrecognized tax benefits of $163 million, including penalties, interest and indirect benefits, would affect our provision for income taxes if recognized.

We are currently undergoing federal income tax audits in the United States (U.S.) and several foreign tax jurisdictions. Transfer pricing calculations are key issues under audits in various jurisdictions, and are often subject to dispute and appeals. The IRS has concluded the examination of our tax returns for our fiscal years through 2010. The IRS commenced the examination of our federal income tax returns for our fiscal years 2012 and 2013 in August 2016.

On September 17, 2010, the Danish Tax Authorities issued a decision concluding that distributions declared in 2005 and 2006 from our Danish subsidiary were subject to Danish at-source dividend withholding tax. We do not believe that our Danish subsidiary is liable for withholding tax and filed an appeal with the Danish Tax Tribunal to that effect. On December 19, 2011, the Danish Tax Tribunal issued a ruling that our Danish subsidiary was not liable for Danish withholding tax. The Danish tax examination agency appealed to the Danish High Court in March 2012. In February 2016, the Danish High Court referred the case to the Court of Justice of the European Union where it was heard before the court in October 2017. We expect the court to issue their opinion and judgment by the end of fiscal 2018.

We continue to monitor the progress of ongoing discussions with tax authorities and the impact, if any, of the expected expiration of the statute of limitations in various taxing jurisdictions.