The AI says that I can look at the Form EIC and it will show me which SSN is causing the issue, but I see no way to do that. Does this work on mobile? Or do I have to access this feature to revise on my computer?
What is the reject code? The 2 digits after the 3 digit code might indicate which dependent. Here’s a couple reject codes that may help
Reject 507 duplicate ssn
Reject code 517
If it thinks another return has been been filed then you have to print and mail your return and let the IRS sort it out.
If a ssn on your return has been used on another return it could be just a mistake and someone else accidentally typed the wrong ssn on their return. Or if your dependent filed a return did he check the box that says he can be claimed on someone else's return?
How to mail a return from the Online version
You can't "fix" this except by printing your correct return, signing it, and mailing it in. The IRS will process your return and pay your refund, and then address any conflicts.
If you did figure out which dependent was the problem, and remove them so you can e-file, you may get much less money, and then it would take 6-8 months to get an amended return with the correct info.
If you claimed the correct dependents based on the rules, file by mail. If you think your child might be a victim of identity theft, you can get an IP PIN for them that will block anyone else from claiming them in the future.
https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin