If you didn't file a 2020 tax return with the IRS, just tell us you didn’t file last year when we ask you. But if you’ve already entered a number for your AGI, manually enter 0 instead.
If you used the Non-Filers tool in 2021 to register for an advance Child Tax Credit payment or third Economic Impact Payment, enter $1 for your prior year’s AGI on your 2021 tax return.