Why are they requesting my 2019 AGI?

[VolvoGirl]

To verify it's you Efiling 2020.

You need your 2019 AGI to efile 2020. The AGI is on 2019 1040 line 8b. 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 2019 or filed it later in the year 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

[DoninGA]

The IRS uses your name, Social Security number and the 2019 AGI for your electronic signature for the e-filed 2020 tax return.

If you did not file a 2019 tax return then indicate that in the File section of the program.  Or you can enter a 0 (zero) for the 2019 AGI if you did not file a 2019 tax return or if the IRS has not fully processed the 2019 tax return that was filed.

The 2019 AGI is on the 2019 Federal tax return Form 1040 Line 8b.