Q. Can I crunch the numbers both ways and go with where the largest refund is?
A. No. As others, have said, it's not optional. There is a rule that says IF somebody else CAN claim him as a dependent, he is not allowed to claim himself. If he has sufficient income (usually more than $13,850), he can & should still file taxes. In TurboTax, he indicates that somebody else can claim him as a dependent, at the personal information section. TT will check that box on form 1040.
Even if he had less, he is allowed to file if he needs to get back income tax withholding. He cannot get back social security or Medicare tax withholding.
https://ttlc.intuit.com/community/dependents/help/when-do-i-have-to-answer-yes-to-being-claimed-as-a...
