The reject email should give a code or reason. The 2 common ones are for a duplicate ssn or the wrong prior year AGI.
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?
If the AGI rejected trying enter 0 for the AGI. That usually works.
How to fix a Rejected return
https://ttlc.intuit.com/community/rejections/help/how-do-i-fix-a-rejected-return/00/26136
How to contact Turbo Tax
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-contact-turbotax/00/26991
What is the Turbo Tax phone number
https://ttlc.intuit.com/community/using-turbotax/help/what-is-the-turbotax-phone-number/00/25632
