Deductions & credits

There is something fundamentally wrong with this tax code or interpretation of the tax code by TurboTax.  What the rule suggests is if someone is legitimately a dependent (>5 months residence and >50% support) and then they move out on their own, they aren't entitled to start an HSA.   In the latter half of the year, they no longer qualify for their parent's health plan (military anyways) and need to legitimately get and start their own health insurance.  We then penalize them for saving any money towards an HSA?  That just can't be right and makes no logical sense.   Can anyone with a tax background legitimately defend why we would not allow or encourage an HSA to be started in this circumstance?