If I mailed in my return do I need to fix the return on here?

[VolvoGirl]

Why did you mail it?  What do you need to fix?

[tholmes091]

Gi number for 2019

[VolvoGirl]

The 2019 AGI?  No you don't need that if you are mailing your return.

Have you mailed it yet?  Maybe you can switch to efile.  Did the AGI reject?

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