If your fiscal year isn’t January through December, you may run into issues with date functionality in Excel. One way to approach it is to insert an IF statement that tests the date.
Say your fiscal year goes from July 1 through June 30, and you refer to that by the ending year. So 7/1/2015, would be identified with FY2016. Assume that 7/1/2015 is entered in cell B1 and 6/30/2016 is entered in cell C1 as references. If the test date is in A4, your formula would be =IF(AND(A4>=$B$1,A4<=$C$1),2016,”invalid year”).