I used an online Non-Filer Tool to sign up to receive advance Child Tax Credit payments during 2021. Why should I file a 2021 tax return during the 2022 tax filing season

You should file a 2021 tax return during the 2022 tax filing season for several reasons, even if you used an online Non-Filer Tool to sign up for advance Child Tax Credit payments during 2021. Filing a 2021 tax return can potentially allow you to receive additional tax credits, including:

1. Any Remaining Child Tax Credit: If you did not receive 100 percent of your Child Tax Credit through advance payments in 2021, you can claim the remaining amount when you file your 2021 tax return.
2. 2021 Recovery Rebate Credit: If you did not receive the total amount of the third-round Economic Impact Payments for which you were eligible, you can claim the Recovery Rebate Credit on your 2021 tax return.
3. Earned Income Tax Credit (EITC): If you had any earned income during 2021, you may be eligible for the Earned Income Tax Credit, which can provide a significant refund.
4. Child and Dependent Care Credit: If you paid someone to care for your child or another qualifying person so you could work or look for work, you may be eligible for the Child and Dependent Care Credit.

Additionally, if you did not receive any monthly advance Child Tax Credit payments in 2021, you can still get a lump-sum payment by claiming the Child Tax Credit when you file your 2021 federal income tax return. This is particularly important if the qualifying children you listed on your 2019 or 2020 tax return (or in the Non-Filer Tool) are the same qualifying children you had in 2021, as you likely only received half of your Child Tax Credit in advance payments.

Filing a 2021 tax return ensures that you can claim any remaining credits and receive the full benefits to which you are entitled.

Sources:
Publication 501 (2023)
Publication 596 (2023)
IRM Part 21. Customer Account Services. Chapter 6. Individual Tax Returns. Section 3. Credits
Publication 5420-A (10/2020)