Here is a really interesting article from the IRS. You may be due a tax refund even if you didn't file a 2018 return.
Some $1.5 billion in unclaimed tax returns may be waiting for an estimated 1.5 million taxpayers who did not file a 2018 Form 1040 federal income tax return.
“In cases where a federal income tax return was not filed,” states the IRS, “the law provides most taxpayers with a three-year window of opportunity to claim a tax refund. If they don't file a tax return within three years, the money becomes the property of the US Treasury.
For 2018 tax returns, your "window" closes on April 18, 2022 for most taxpayers. Taxpayers living in Maine and Massachusetts have until April 19, 2022. The law requires taxpayers to mail and make sure the tax return is postmarked by that date.
Of course, not filing a tax return is not a good idea. There is a clear drawback.
The IRS reminds taxpayers seeking a 2018 tax refund that their checks "may be placed on hold if they haven't filed tax returns for 2019 and 2020. In addition, the refund will be applied to any amounts still owed to the IRS or a state tax agency and can be used to offset unpaid child support or overdue federal debt, such as student loans.”
By not filing a tax return, “people can lose more than just the refund of taxes withheld or paid during 2018. Many low- and moderate-income workers may be eligible for the Earned Income Tax Credit (EITC). By 2018, the credit was worth as much as $6,431.”
As with anything related to the IRS, there is a catch. If you are due a refund for the 2018 tax year, you must act by the April 18 (2022) tax deadline.