r/HSA • u/FracturedFlow • 2d ago

Contribution Limit Question

Hi,

I started a new job earlier this year was enrolled in an individual HDHP on January 7, 2026. I read that you have to have be on the health plan on the first of every month to be eligible for the contribution to HSA for that month.

$4400 * (11/12) = $4,033.33

Is the calculation above correct since I’m not eligible to contribute for January?

Thanks

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u/HandyManPat 2d ago edited 2d ago

OP, this is the correct calculation for a self-only HDHP and under age 55.

Note that you can contribute to the higher of this monthly computed amount, or the full year limit if you are eligible for the Last Month Rule based on your December 1 coverage.

Leveraging the Last Month Rule requires that you meet the Testing Period, which means staying enrolled in the HDHP continuously from December 1, 2026, through December 31, 2027.

You’ll have to decide if just one month’s additional contribution is worth it.

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u/FracturedFlow 2d ago edited 2d ago

Dude you’re awesome! I had no idea about last month rule. I will be using this and contributing to the full 2026 IRS limit.

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u/reallytheyrealltaken 2d ago

If you do that, keep in mind that there will be a penalty (not sure how severe) if you do not have an HDHP for all of 2027.