Rejected Tax return

There's got to be another reason.  The 1040 is the form they filled out and filed.  You need the exact reject message or code.   Did it reject for the wrong 2022 AGI?  That's a common reason.  You need to enter your 2022 AGI to efile 2023.  Did they file a Joint return for 2022?  You enter the same AGI for each of them.    

Sounds like they misunderstood.  If they filed a joint return for 2022  --- it was ON a Form 1040.   Form 1040 is their tax return.      They need to enter the AGI that is on line 11 of that form.   The amount is the same for each of them.   If the amount from their line 11 does not work and let them e-file, they can try to use "zero" instead.   If neither of those work, they can file by mail.