Enrolled in Medicare.
Beginning with the first month you are enrolled in Medicare, your contribution limit is zero. This rule applies to periods of retroactive Medicare coverage. So, if you delayed applying for Medicare and later your enrollment is backdated, any contributions to your HSA made during the period of retroactive coverage are considered excess. See Excess contributions, later.
Example.
You turned age 65 in July 2024 and enrolled in Medicare. You had an HDHP with self-only coverage and are eligible for an additional contribution of $1,000. Your contribution limit is $2,575 ($5,150 × 6 ÷ 12).
