If you're entitled to a tax refund, such as if your employer withheld too much in taxes or you qualify to claim refundable tax credits, you must file your tax return if you want your money back. If you don't file a return, the Internal Revenue Service won't know you are entitled to a refund.

Time Limits

When you're entitled to a refund, the April 15 deadline isn't quite as important, because you can file up to three years after the initial filing deadline and still get your money back. If three years pass, you forfeit the refund. For example, you would have until April 15, 2017 to file and get a refund to which you were entitled for the 2013 tax year.