<human>: My boyfriend notified me that his mother wants to claim him as a dependent. He is 27 years old, worked for more than half the year, and lives with his mother. I do as well. She didn't support him (I did), and only let him off by not charging him rent. Her mortgage payment is only $800. I pay $450 (for the back room we share) and his sister pays $450. I pay for our supplies, toiletries, food, and the internet bill. Now, the issue is he already filed his taxes as an independent, as he rightly should have. My question is, what will happen if she tries to claim him? Apparently she spoke to her tax representative and he advised he just needs his birth certifcate. Will this come back on him in the end, or his mother? He told her not to do it, but she is continuing with it anyway.

Summarize the given text in a few sentences.
<bot>: Boyfriend's mother is trying to claim him as a dependent after he already filed as an independent. Boyfriend is 27 and supported himself for over half the year. What will happen?