Still Working at 65? How Employer Coverage and Medicare Fit Together

Every autumn the Medicare advertising starts, and every autumn we hear from people who are still working, still covered at work, and now genuinely unsure whether they’re supposed to be doing something about Medicare.

Here’s the reassuring part: for many people who are still working at 65, the answer is not yet. For others, delaying is a costly mistake that quietly goes unnoticed until a hospital bill arrives. The difference between those two groups comes down to a handful of rules that nobody explains until you ask.

First: Part A and Part B are separate decisions

Most people at 65 take Part A (hospital insurance) because it’s premium-free if you or a spouse worked and paid Medicare taxes for about 10 years. There’s usually no downside — with one significant exception involving HSAs, which we’ll come to.

Part B (medical insurance) carries a monthly premium. That’s the one worth thinking carefully about while you’re still covered at work, because paying two premiums for overlapping coverage helps nobody.

The question is never “should I take Medicare?” It’s “should I take Part B yet?”

The rule that decides it: how big is the employer?

This is the part almost nobody knows, and it determines who pays your claims first.

That second row is the dangerous one. If Medicare is the primary payer and you don’t have Part B, your employer plan may pay only the share it would have paid second — which can leave you responsible for most of the bill. People discover this after a surgery, not before.

The HSA trap that catches people six months early

If you contribute to a Health Savings Account, this one deserves your full attention, because the timing is counterintuitive.

You cannot contribute to an HSA once you have Medicare. Fair enough — but here’s the catch the 2027 handbook spells out: when you sign up for premium-free Part A (or claim Social Security), Part A coverage can be backdated up to six months, though never earlier than your first month of eligibility.

So the month you enroll is not necessarily the month your Medicare started. If you kept contributing during those retroactive months, you’ve made excess contributions and may owe a tax penalty.

The practical rule: stop HSA contributions at least six months before you plan to enroll in Part A or claim Social Security. Our HSA and Medicare guide covers how this interacts with a working spouse and family coverage, and it’s worth reading before you set next year’s payroll elections.

When you do retire: the 8-month window

When coverage based on current employment ends, Medicare gives you a Special Enrollment Period of 8 months to sign up for Part B without a late penalty. That’s generous — and it’s where the biggest trap in Medicare lives.

If you’re offered COBRA at retirement and you’re 65 or older, treat that as a moment to get advice, not a moment to relax.

What the Part B penalty actually costs

The Part B late enrollment penalty is roughly 10% of the standard premium for each full 12-month period you could have had Part B and didn’t — and unlike most penalties, you pay it for as long as you have Part B. It doesn’t expire.

Delay three years without a valid reason and you’re looking at roughly 30% added to your premium, every month, for the rest of your life. That’s why the employer-size question is worth a phone call to HR rather than an assumption.

Don’t forget drug coverage

While you’re weighing Part B, check one more thing: whether your employer’s prescription coverage is creditable — meaning Medicare considers it at least as good as Part D.

Your plan must tell you each year in writing whether your drug coverage is creditable. Keep those notices. If your coverage is creditable, you can delay Part D without penalty. If it isn’t and you delay anyway, the Part D penalty works much like Part B’s: permanent, and calculated from how long you went without.

And no — this isn’t an Annual Enrollment decision

This is worth saying plainly in September, because the advertising will suggest otherwise.

The Annual Enrollment Period, October 15 to December 7, is for people already on Medicare who want to change Medicare Advantage or Part D plans. If you’re still working and covered at your job, your Medicare timing runs off your employment, not off the calendar. Your window opens when your employment coverage ends, whenever in the year that happens.

So if you’re still working, the flood of October mail is mostly not about you. What is about you: confirming your employer’s size, checking whether your drug coverage is creditable, and knowing what you’ll do in the eight months after you retire.

Frequently asked questions

Do I have to take Medicare at 65 if I’m still working? Not necessarily. Most people take premium-free Part A, and whether you need Part B depends primarily on your employer’s size and how the plan coordinates with Medicare.

My employer has fewer than 20 employees. What should I do? Talk to your benefits administrator and to a licensed agent before your 65th birthday. In small-employer situations Medicare generally pays first, and going without Part B can leave you exposed to most of a bill.

Can I keep my HSA after 65? You can keep the account and spend from it — including on Medicare premiums. You just can’t keep contributing once Medicare starts, and Part A’s six-month backdating means your last contribution should come well before you enroll.

Does COBRA count as employer coverage for Medicare? No. That’s the trap. Your Part B Special Enrollment Period runs from when employment-based coverage ends, regardless of COBRA.

What if I’m covered through my spouse’s job? The same employer-size logic generally applies, based on their employer. Confirm with that plan’s administrator, since it’s their rules that govern.

I already delayed and I think I made a mistake. Is it fixable? Sometimes. There are equitable relief provisions for people given incorrect information by a federal employee, and Special Enrollment Periods for specific circumstances. It’s worth asking rather than assuming the penalty is permanent — but ask promptly.

Do I need to do anything during Annual Enrollment if I’m still working? Usually not. AEP is for changing Medicare Advantage and Part D plans. Your decisions are tied to your employment instead.

Get the answer before your birthday, not after

Almost every expensive version of this story starts the same way: someone assumed their situation matched a friend’s, or assumed COBRA counted, or assumed they’d sort it out later. Almost every easy version starts with one conversation a few months early.

If you’re approaching 65 and still working — or planning to retire in the next year — reach out for a free, no-obligation review or call 904-654-5450. We’ll work out whether you need Part B now, what your employer’s size means for you, how your HSA fits, and what your timeline looks like when you do retire. Kate Spilsbury (RSSA®, CMIP®) is an independent, licensed agent based in Jacksonville, serving Northeast Florida and Camden County, GA. If you’re newly approaching Medicare, our turning 65 checklist is a good place to start.

This article is educational and not medical, tax, or legal advice. Coordination rules depend on your specific employer, plan, and circumstances — confirm yours with your benefits administrator and official Medicare resources. Mere Benefits is not connected with or endorsed by the U.S. government or the federal Medicare program. We don’t offer every plan available in your area.