The IRS will be sending out two letters to certain individuals with information needed to file their 2021 tax returns. People who received the Advanced Child Tax Credit will receive Letter 6419 sometime between late December and mid January, which will include the total amount of the credit and the number of qualifying children. People who received the third Economic Impact Payment (stimulus payment) will receive letter 6475, which will help people determine if they are entitled to and should claim the Recovery Rebate Credit. This letter should be received in late January. Save both these letters if you receive them with your other important tax documents; you will need them to file your return.