I got this reject code but when I checked IRS online for my wife's filing status for 2025 it is stating "not filed". We both have ID Me accounts setup so I don't understand why we are getting this reject code & IRS is showing we did not file as yet.
You are correct, this reject is when the spouse's SSN in the return must not be the same as the Primary SSN on another return filed for the same tax year.
You should verify that the information is correct, name, SSN, date of birth, if there is a correction needed do it and resubmit. If everything is correct, you will have to contact the IRS for further guidance and file by mail.
It would be recommended to file a report of identity theft.
Everything is correct for my spouse and IRS online filing status is showing nothing was filed by her. Is it possible that someone used her SSN to claim her as a dependent?