HSAs and Employees Nearing Medicare: What Your Communications Should Say

Unlocking the Potential of HSAs: A Guide for Late-Career Employees

The HSA is usually the least explained benefit in a program and the one where a quiet mistake costs an employee real money. The group most exposed is your employees in their early sixties, and the mistake is almost always the same one.

It is worth caring about for two reasons. The employee absorbs a tax penalty that was entirely avoidable, and the conversation that follows lands on HR. Neither is a plan design problem. Both are a communication problem, which makes them fixable.

Key takeaways for employers

Medicare Part A can be backdated up to six months when an employee enrolls after 65. HSA contributions made in that window become excess contributions carrying a 6 percent excise tax.
The practical rule your communications should carry is to stop HSA contributions six months before applying for Medicare or Social Security.
Enrolling in Part A or Part B ends HSA contribution eligibility entirely, catch-up included, starting the month coverage begins.
For 2026 the limits are $4,400 self-only and $8,750 family, plus a $1,000 catch-up for anyone 55 or older at any point in the year.
An employee can still spend HSA dollars after enrolling in Medicare, including on Part B premiums. Only contributions stop.

The six-month lookback, and why it catches people

An employee works past 65, stays on your plan, and keeps contributing to their HSA. That is all correct and permitted. Later they apply for Medicare or Social Security, and Part A is backdated up to six months from the application.

Those backdated months are months in which the employee was, retroactively, enrolled in Medicare. HSA contributions made during them were never eligible. They become excess contributions, subject to a 6 percent excise tax for every year they remain in the account.

What the employee did	What actually happened	Result
Turned 65, stayed on the group plan, kept contributing	Fully eligible. No issue at all.	No penalty.
Applied for Medicare or Social Security at 66 without pausing contributions	Part A backdated up to six months	Contributions in the backdated window become excess. 6% excise tax per year until corrected.
Stopped contributions six months before applying	No overlap between contributions and retroactive coverage	No penalty.

Nothing about this is intuitive. An employee doing everything else right walks into it, and the first time anyone mentions it is often after the fact.

Catch-up contributions are quietly underused

Anyone 55 or older at any point in the year can add $1,000 above the standard limit. It applies for the whole year even if the birthday falls in December.

In practice this is one of the least claimed provisions in a benefits program, because it requires an employee to actively raise their election. Nobody is defaulted into it. A single line in your enrollment materials aimed at employees over 55 changes the take-up rate more than anything else you could do here.

2026 limit	Standard	With catch-up at 55+
Self-only	$4,400	$5,400
Family	$8,750	$9,750

What your communications should actually say

The gap is rarely knowledge of what an HSA is. It is the sequencing around Medicare. Four things are worth stating plainly and in writing:

Turning 65 does not end HSA eligibility. Enrolling in Medicare does. Employees who stay on the group plan can keep contributing.
Stop contributions six months before applying for Medicare or Social Security, because Part A can be backdated.
Eligibility ends the month Medicare coverage begins, and the catch-up ends with it. Prorate the annual limit accordingly.
Spending does not stop. HSA funds remain available after Medicare enrollment, including for Part B premiums.

Timing matters as much as content. This belongs in a targeted message to employees approaching 63 or 64, not buried in the general open enrollment packet where the people who need it will not see it.

Two plan design questions worth asking

Most of this is communication, but two items sit with you and your vendor.

Does your HSA administrator support investing, and at what threshold? Many require a minimum cash balance, commonly somewhere between $1,000 and $2,500, before funds can be invested. Employees with balances above that threshold who have never been told are holding a long-horizon account in cash.

Are your enrollment materials age-aware? A single set of HSA materials written for a 35-year-old will not serve a 63-year-old, and the 63-year-old is the one facing a penalty.

Frequently asked questions

Can our employees keep contributing to an HSA after they turn 65?

Yes, as long as they remain on a qualifying high deductible health plan and have not enrolled in Medicare. Age alone does not end eligibility.

What is the six-month lookback?

When someone enrolls in Medicare after 65, Part A coverage can be backdated up to six months from the application date. HSA contributions made during that retroactive period become excess contributions, subject to a 6 percent excise tax for each year they remain in the account.

When should an employee stop contributing?

At least six months before they apply for Medicare or Social Security. That is the practical rule worth putting in writing.

Do the catch-up contributions stop too?

Yes. Once Medicare coverage begins, all HSA contribution eligibility ends, including the $1,000 catch-up.

Can they still use the money after enrolling in Medicare?

Yes. Existing HSA funds remain available for qualified expenses, and Medicare Part B premiums are a qualified expense. Only new contributions stop.

Talk it through with us

If you are not sure what your current HSA communications say to employees approaching Medicare, send them over and we will read them with you. We advise employers across Maryland, DC and Northern Virginia, and this is a short review with a clear outcome.

Get a real review of your current coverage