No, he’s still your dependent. If he were paying for his own expenses then he wouldn’t be considered a dependent and could open his own HSA.

This would indicate YES- but it's fuzzy to me what the maximum contribution is. You might get more clarity from your vendor...

https://livelyme.com/blog/can-i-open-an-hsa-for-my-child/

No. The IRS sets the limits as individual for single policy holders or family for those covering themselves + 1 or more. So the family HSA that you have is all that can be set up for the 1 policy that you have.

I don’t think he can since he can be claimed as a dependent (even if you don’t claim him) but I’m not 100% sure.

DC is 19 y.o and is currently doing an internship where he expects to gross about 15K this summer. He will be contributing to a Roth. I was wondering if he can also contribute to an HSA if we did not claim him as a dependent on our joint tax return. He's currently on our family HDHP plan through my employer.