Illinois Mail Return and Federal 1040

[rubyp]

Three of us are going to mail our Illinois returns but when we do Print "all official forms required for printing" one of us has the federal 1040 at the bottom and the other two do not.

I don't understand why this is happening, from what I see Illinois should not need the federal 1040 for this return. And if Illinois wants it then why don't the other two also have the federal 1040 also printing out.

Should I just trust Turbotax logic and send one Illinois return with the federal 1040 and the others without?

[LeticiaF1]

It depends, there are some situations where the form instructs to attach some parts of the federal return.   See the image below of the 2023 Form IL-1040, see line 5, it asks to have page one of federal return attached.  It could be possible that only one of you have an amount in a line that requires a copy of the federal return and the others do not.