Medicare · Turning 65

Still Working at 65? Here's How to Decide Between Your Employer Plan and Medicare

"I have coverage through work, so I'll deal with Medicare when I retire." That's right for some people and expensive for others — and the thing that decides which is how many employees your company has.

Viva Insurance Group · Serving Miami-Dade, Broward, and all of Florida

Small business owner in his mid-sixties reviewing paperwork in his workshop

More people are working past 65 than at any point in modern memory. South Florida especially — business owners, contractors, people driving for themselves, people who simply like their job.

And this is, without much competition, the most confusing corner of turning 65. The rules are genuinely counterintuitive, the penalties are permanent, and almost nobody at your job is qualified to advise you on it.

Let's go through it properly.

The question that decides everything: how big is the employer?

Not your salary. Not your title. Not how good the plan is. The head count.

20 or more employees

Your group health plan pays first, and Medicare pays second. Because that coverage counts as active employer coverage, you can generally delay Part B without a penalty for as long as you or your spouse is actively working and covered.

When the job or the coverage ends, a special enrollment period opens and you sign up then. No penalty.

Fewer than 20 employees

Here's the one that hurts. At a small employer, Medicare generally pays first and your group plan pays second.

Which means if you didn't enroll in Part B, there is no primary payer for the services Part B would have covered — and your group plan can pay as though Medicare had already paid its share. People discover this after a hospitalization, when a claim comes back with a balance they weren't expecting.

If you work for a small employer, in most cases you should enroll in Part B at 65. Confirm it with your plan administrator in writing before you decide anything else.

Ask HR one question, and get the answer in writing: "Does this plan pay primary or secondary to Medicare for employees age 65 and over?" That single sentence resolves most of this article.

The COBRA trap

This one costs people real money, and it is almost always an honest mistake.

COBRA is not active employer coverage. Neither is retiree coverage. Neither is a plan you bought on the Marketplace.

The exception that lets you delay Part B without penalty requires coverage based on current, active employment — yours or your spouse's. The moment the employment ends, the clock starts, even if you're still holding a card from that same insurer.

So the sequence that goes wrong looks like this: someone retires at 65, elects 18 months of COBRA because it's familiar, and assumes they're covered. They are covered — but they're also accruing a Part B late enrollment penalty and burning through the special enrollment period they didn't know had started.

You get eight months from the end of employment or the end of employer group coverage, whichever comes first, to enroll in Part B without penalty. COBRA does not extend it. Retiree coverage does not extend it.

The HSA rule with the six-month tail

If you contribute to a health savings account, this affects you and the timing is unusual.

Once you're enrolled in any part of Medicare — including premium-free Part A — you can no longer contribute to an HSA. Excess contributions can trigger an IRS excise tax. You can still spend what's in it, tax-free, on qualified expenses including Medicare premiums. You just can't put more in.

The part that surprises people: when you enroll in Medicare after 65, Part A coverage can be backdated up to six months (never earlier than the month you turned 65). Contributions you made during those retroactive months become excess contributions, with tax consequences.

The practical rule: if you plan to enroll in Medicare, stop HSA contributions six months before your enrollment date. Tell your payroll department early — they will not catch this for you.

Even if you delay Part B, look at Part A

Part A is premium-free for most people who've worked about ten years. If you're not contributing to an HSA, enrolling in Part A at 65 while you keep working is usually harmless and can help with hospital costs alongside your group plan.

If you are contributing to an HSA, that free Part A is exactly what ends your contributions. This is the fork in the road, and it comes down to whether the HSA tax benefit is worth more to you than the secondary hospital coverage. It's a real calculation, not a default.

Don't forget drug coverage

Your employer plan probably includes prescription coverage. The question is whether it's creditable — meaning at least as good as standard Medicare Part D.

Your plan is required to tell you, in a notice that goes out each fall. Find it and keep it. If your drug coverage is creditable, you can delay Part D with no penalty. If it isn't, you're accruing a Part D penalty quietly, month by month, and it's permanent once it starts.

Small employers and some association plans are the ones most likely to fall short here. Don't assume.

Is your group plan even the better deal?

Worth asking honestly, and the answer isn't always what people expect.

Run the comparison on:

What you pay per month. Your share of the group premium versus the Part B premium plus whatever Medicare coverage you'd add.
Deductibles and out-of-pocket maximums on both sides.
Your spouse and dependents. This is often the deciding factor. Medicare covers you alone. If your family is on your work plan, leaving it means finding coverage for them.
Your doctors and your prescriptions under each option.

For someone at a large employer with strong family coverage, staying put is often clearly right. For a self-employed person paying the full freight of an individual plan, Medicare at 65 is frequently the cheaper and better answer. Both conclusions are common. It depends on your numbers.

What to do, in order

Ask HR whether the plan pays primary or secondary at 65, and get it in writing.
Find your creditable coverage notice for prescriptions.
If you have an HSA, work backward six months from any planned Medicare enrollment date and stop contributions then.
Compare total annual cost of staying versus moving — including your family.
Mark the eight-month window. When employment or group coverage ends, that clock starts. COBRA does not pause it.
Remember the Medigap window. Your six months of guaranteed-issue Medicare Supplement rights start when you're 65 and enrolled in Part B — whenever that turns out to be.