- The IRS estimates 1.5 million taxpayers did not file a 2018 tax return to claim tax refunds worth more than $1.5 billion. The three-year window of opportunity to claim a 2018 tax refund closes April 18, 2022, for most taxpayers. If they do not file a 2018 tax return by April 18, 2022, the money becomes the property of the U.S. Treasury. The law requires taxpayers to properly address, mail and ensure the 2018 tax return is postmarked by that date.
