No it would actually be a form of tax fraud. Your 18 year old CAN be claimed as a dependent. As such, he is required to say on his own return that he can be claimed as someone else's dependent. He cannot choose whether he is a dependent or not---he is supposed to follow the tax law---and that is probably what you as a parent really want to teach him.
https://ttlc.intuit.com/community/dependents/help/when-do-i-have-to-answer-yes-to-being-claimed-as-a...
**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.**
