You can spend HSA funds tax-free for qualified medical expenses at any age and regardless of what kind of insurance you have.
If you are over age 65, you can withdraw funds and pay regular income tax but you are not charged the additional 20% penalty. If you made a withdrawal in the year you turned 65, and did not use it for medical care, but you are being charged a penalty, let us know and we can research how to address that in Turbotax.
You can't make new contributions if you have "other" medical coverage (not an HDHP). Other coverage includes Medicare. You don't have to join Medicare when you turn 65 but most people do, and whenever you do join Medicare, you are not eligible to make new contributions. You can still withdraw funds that were previously contributed.
