The 2023 AGI is on your 2023 federal tax return, Form 1040 Line 11
To access your prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
Start the 2024 online tax return by entering some personal information then click on Tax Home on the left side of the screen.
On the Tax Home webpage -
Scroll down to the section Your tax returns & documents. Click on the Year 2023 and Click on Download/print return (PDF) or Click on View adjusted gross income (AGI)
Where do I find my AGI?
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
Your 2023 tax return shows your 2022 Adjusted Gross Income (AGI) If you filed a joint return then the AGI is the same for each of you.
Form 1040 line 11
If entering the amount from your 2023 tax return does not work, then try entering “0” instead. If that does not work and you still cannot e-file, then print, sign, and mail your tax return.
You can get a free transcript of your past return from the IRS: