If you established an HSA before you enrolled in Medicare, you can still use the funds from the account. But in order to save to an HSA, you must be enrolled in an HSA-eligible health plan and you can’t be covered by other insurance, such as Medicare. This means you can’t contribute to an HSA (or establish an account if you don’t have one) once you’re enrolled in Medicare.
There’s a six-month contribution look-back period if you sign up for Medicare after age 65 (although not before the month you turn 65), which means you receive retroactive health coverage and can’t make contributions during that period.
