(WJW) — Those who received a third stimulus check in 2021 should soon be getting a letter in the mail from the Internal Revenue Service for tax-filing purposes.

“People receiving these letters should keep them,” the IRS said in a statement. “Do not throw them away.”

The letters are meant to help with your 2021 tax returns by more thoroughly explaining how to claim your economic impact (stimulus) payments, which aren’t taxed but still must be claimed.

But what if you are missing a stimulus payment?

Are you entitled to a recovery rebate credit, and should you apply for one? The explanatory letter will walk you through the process, telling you how much stimulus money you received, including any “plus-up payments,” and any extra dollars still owed to you.

Worth up to $1,400 for recipients and any dependents, third stimulus checks started being sent out last March.

The letters are supposed to start being sent by the end of January. A separate letter is also being sent to those families who received child tax credit payments last year.

The passage of the CARES Act sent out a first round of direct payments to American taxpayers in April 2020. Those checks were followed by another round of payments in December 2020 and then a third round under the American Rescue Plan in 2021. The IRS also started issuing monthly payments to families with children in July 2021 as an advance for the increased child tax credit.

Find out more about filing your tax returns, which are due on April 18, by visiting the IRS website.