You can not contribute to an HSA when you are on Medicare. You can only contribute to an HSA when you have a high-deductible health plan (HDHP) and are under 65. Once you turn 65 or are on Medicare, you cannot continue contributing to the HSA.

You are the owner of your HSA, not your employer, and you can contribute until you turn 65. You can use the HSA funds for qualified medical expenses, regardless of whether or not you are currently enrolled in Medicare.

Once you turn 65, you have more flexibility in spending the HSA funds. However, you may not continue to contribute to the HSA.