Here’s a weird little piece of the U.S. tax code. You can enroll in Medicare. Your HSA doesn’t disappear. You can keep spending the money. You can even use it for certain Medicare premiums.
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But you generally cannot put another dollar into the HSA once Medicare starts.
That sounds simple. It isn’t. Because Medicare has a sneaky little trick. Your Medicare coverage can sometimes start months before you think it does.
And that can turn an innocent HSA contribution into an excess contribution.
Which means taxes. Potentially recurring taxes.
Welcome to retirement planning. Where “I signed up for health insurance” somehow becomes a multi-step tax puzzle.
The IRS’s HSA rules in Publication 969 make the central rule clear: once you become enrolled in Medicare, your HSA contribution limit becomes zero beginning with the first month of Medicare enrollment.
But that does not mean you lose your HSA. That distinction is the whole game.