Since his return has been rejected, he can follow the instructions below (if he filed using TurboTax Online) to fix this:
- Sign into your TurboTax Online account
- Click on Take me to my return
- Open the Navigation bar on the left side of the screen
- Click on the My Info tab
- Scroll down to #3, which is the question about someone else being able to claim you
He can then resubmit his return electronically.