In addition to the information provided by SuperUser rjs, if your son had federal/state tax withheld by his employer, he can file a tax return to seek a refund of federal and state tax withheld. He just needs to say on his own return that he can be claimed as a dependent on someone else's return.
**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.**
