Yes, the HSA contribution/health care eligibility/tax dependent puzzle is not an easy thing to figure out. Ask me how I know that. When my daughter became a tax dependent, I found out that she was no longer able to be a beneficiary under a parent’s HSA, even she was still eligible to be on the parent’s health plan (until she turns 26). She opened her own HSA, and it was easy enough to back out the previous HSA transactions that shouldn’t have happened, but a lot of these rules aren’t obvious enough to easily follow.