Federal section
in the personal worksheet for your spouse, it asks for the state of residency on 12/31/2025? did you answer this
then it asks if she was a part-year resident of that state for which you should check the box
then it asks for the date residency was established in that state enter the date
then it asks for the previous state of residency for which you should enter IL.
in the Illinois info worksheet check part-year resident. But there's a bug as you noticed because it only asks for one of the taxpayers. the actual Il-1040 does not ask it this way. Rather on form Il-1040-NR each of you enter your dates of illinois residency and for your spouse the other state and dates of residency.
[MODS BUG ILLINOIS INFO WORKSHEET JOINT RETURN one a part year illinois resident - only asks for one taxpayer]
