The 1040 is the tax return you filled out and filed. You should always save the pdf each year after you file.
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
How to access prior online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/01/270...
You have to log in to the same account. You need to start entering some basic Personal Info in 2021 for the side menu to open up. Just continue a little ways into 2021.
If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online.
