Why Can Medicare Make Your HSA Contribution Limit Zero?

You can turn 65. Keep working. Keep your high-deductible health plan. Keep your HSA. Keep saving. Then Medicare arrives.

And suddenly the IRS says: Your HSA contribution limit is zero.

Not $1. Not a reduced amount. Zero.

Sounds harsh. But there's a reason.

And one particularly weird Medicare rule makes this much more important than it looks.

Your Medicare coverage can sometimes start retroactively.

So you can make an HSA contribution today...

...and later discover Medicare says you were already covered months ago.

Congratulations.

You may now have an excess HSA contribution.

This is one of those retirement rules that looks ridiculous until you understand how the two systems overlap. Let's unpack it.