Being asked what my 2020 AGI was for this years return. Line they are telling me to find it is blank. Do I put 0? There are other lines that say AGI amount...?

[Critter-3]

Look at line 11 of the form 1040 ... if there is no number on that line then enter a zero for the AGI. 

[rjs]

Are you sure you're looking at the right form? On the 2020 Form 1040 there is only one line that says "This is your adjusted gross income." That's line 11. It doesn't say "AGI amount." It says "This is your adjusted gross income."

[VolvoGirl]

You need your 2020 AGI to efile 2021. The AGI is on 2020 1040 line 11. If you filed a Joint return you use the same AGI for each spouse.

How to find the AGI.
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947

If you didn't file 2020 or filed it later in the year or mailed it, then try entering 0 for the AGI. If that doesn't work you will have to print and mail your return.

Or request a transcript from the IRS
https://www.irs.gov/individuals/get-transcript