Your son made a mistake very common among teenagers and students filing their own tax returns--and then you as parents are the ones who are inconvenienced. Your son's return has to be amended. You do not have to wait around for him to do that. You can either print, sign and mail your own tax return that claims him, or you can obtain an IP PIN for him and try to e-file again.
GET IP pin in order to e-file if your dependent’s SSN was claimed on another return
https://www.irs.gov/newsroom/irs-takes-steps-to-help-prevent-refund-delays-by-accepting-duplicate-de...
https://www.irs.gov/identity-theft-fraud-scams/get-an-identity-protection-pin
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
