For U.S. tax purposes, IRS regulations require you to determine whether you were or will be substantially present in the U.S. for the current year and preceding two years. To determine if you meet the substantial presence test for 2016, enter the number of days you anticipate you will be present in the U.S. during 2016 in the "current year" box, enter the number of days you were present in the U.S. during 2015 in the "1st prior year" box, and enter the number of days you were present in the U.S. during 2014 in the "2nd prior year" box. In general, you must count any day you were or will be physically present in the U.S. at any point in time.