Per IRS guidance (https://www.irs.gov/businesses/small-businesses-self-employed/filing-past-due-tax-returns:(
"If you are due a refund for withholding or estimated taxes, you must file your return to claim it within 3 years of the return due date. The same rule applies to a right to claim tax credits such as the Earned Income Credit."
The filing deadline for the 2015 individual tax return was April 18, 2016. So in order to claim any refund, you will need to file by April 18, 2019.
[edited 2/24/17, 8:25pm]
