In the IRS Issue number IR-2021-75, the IRS indicates that there is $1.3 billion of refunds that have not been claimed by the taxpayers in 2017. Keep in mind, that the law provides a three-year window to claim a refund. Normally, April 15, 2021, is the deadline to claim a refund from tax year 2017 but, the IRS has extended it to May 17, 2021. To get the unclaimed refund, a taxpayer must properly address and mail the tax return, postmarked by May 17, 2021. If a taxpayer doesn’t file a return within three years, the money becomes property of the U.S. Treasury.