if you file jointly in 2023, both your AGIs for Illinois should be the same as line 11 on the federal 1040 which should agree with line 1 on the 2023 Illinois 1040. if not you need the separate AGIs from the separate 2023 returns.
agi is only one of several verification methods. this is from Illinos
If you did not receive a booklet in the mail, go to Illinois Department of Revenue's web site at www.revenue.state.il.us or call 800-732-8866 to obtain your IL-PIN. Have your driver's license and last years tax return available when you make this call.
To assure your return will be processed successfully, you may provide one of the following optional items in addition to the mandatory IL-PIN:
* Prior Year Adjusted Gross Income, IL-1040 Line 1
or
* Primary or Spouse's Drivers License
getting an iL-pin
https://mytax.illinois.gov/_/
