The IRS requires that you enter the 2023 AGI (Adjusted Gross Income) when e-filing the 2024 tax return for your electronic signature.
The 2023 is on on the 2023 federal tax return, Form 1040 Line 11
If you did not file a 2023 return, either indicate that in the File section of the program or enter a 0 (zero) for the 2023 AGI