No. You cannot have it both ways. You can claim his medical expenses IF he is a dependent on your tax return. A dependent does not get to "choose" whether they are claimed. If your son can be claimed, then his return is supposed to say that he can be claimed, even if no one actually claimed him.
**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.**
