Do I need to sign up for Medicare at 65 if I'm still working?

Usually not — if you are actively working and your employer group health plan comes from a company with 20 or more employees, you can wait to take Part B and there is no penalty for waiting. That one number, 20, decides most of this. Everything else in this article is the exceptions, and the exceptions are where the money is.

I have this conversation a lot in north Peoria. Vistancia, Trilogy, Blackstone and the newer 85383 subdivisions are full of people who are 65 and not done working — running a business, consulting three days a week, or still on the payroll of an employer in Illinois or Minnesota while working from a house off Lake Pleasant Parkway. Turning 65 arrives with a stack of mail telling all of them the same thing, and for a good share of them the mail is wrong.

Do I need to sign up for Medicare at 65 if I’m still working?

Medicare’s own rule reads simply enough: if you or your spouse are still working and have group health coverage available to everyone at the company, you can wait until that work or that coverage ends to sign up for Part B, and you will not pay a late enrollment penalty.

The word doing the work in that sentence is current. Coverage has to come from a job somebody is actively doing right now — yours or your spouse’s. The moment the coverage is a leftover from a job that ended, the protection is gone, whatever the plan is called.

So the honest version of the question is not “am I still working?” It is:

1. Is the coverage from current employment — yours or a working spouse’s?
2. Does that employer have 20 or more employees?
3. Is the drug coverage creditable, and can they show you that in writing?

Three yeses and you can generally leave Medicare alone for now, other than the Part A decision below. Any no, and the calendar starts moving.

The 20-employee rule is the whole answer

Under Medicare’s coordination-of-benefits rules — the “working aged” provisions — a group health plan pays first and Medicare pays second when the covered person is 65 or older, the coverage is based on current employment, and the employer has 20 or more employees. Part-time employees count toward that 20. In a multi-employer plan, it is enough that one participating employer is at 20.

Flip it around and the picture changes completely. At an employer with fewer than 20 employees, Medicare generally pays first once you are eligible, and the group plan pays second — which means that if you have not enrolled, there is no first payer at all. The plan can legitimately pay a small fraction of a hospital bill and leave you the rest.

This is the single most expensive misunderstanding I see, and it lands hardest on exactly the households this end of the Valley is full of: the owner of a 9-person company, the professional practice with a handful of staff, the family business one adult child now runs. Being the employer does not exempt you from the rule; the rule is about headcount, and it is your HR or benefits administrator — not your insurance card — who can tell you the number.

Ask them, in writing, two questions: how many employees does this plan count for Medicare secondary payer purposes, and is this plan’s prescription drug coverage creditable for Part D. Both answers should come back on paper.

Should I take Part A at 65 anyway?

For most people Part A costs nothing — you earned it through 40 quarters of Medicare taxes — and taking it while you keep working can quietly pick up some inpatient costs your group plan does not. That is why the default advice is usually “take Part A, delay Part B.”

There are two situations where that default is wrong.

If you are still contributing to a Health Savings Account. Any Medicare enrollment, Part A included, ends HSA contribution eligibility, and Part A can be granted retroactively up to six months. Medicare’s own guidance is to stop HSA contributions six months before you apply for Medicare or Social Security. Contribute past that line and you are looking at a correction and possibly a tax penalty. I wrote the counting method out in full in Can I contribute to an HSA while on Medicare? — read that one before you sign anything if there is an HSA in the picture.

If you are not premium-free. Some people — a spouse with limited work history, or someone whose career was mostly outside the US system — have to buy Part A, and then the calculus is a real one. The Part A premium checker walks through the quarters test.

One more thing worth knowing before you file for anything: claiming Social Security at or after 65 enrolls you in Part A automatically. People aiming to delay Social Security to 70 are often surprised that the two decisions were ever connected. They are, and only in that direction.

What does not protect you: COBRA, retiree plans and the Marketplace

This is the part of the article I would print and put on the refrigerator.

• COBRA does not extend your Medicare window. Your eight-month Special Enrollment Period starts when the employment or the job-based coverage ends — not when COBRA runs out. Someone who retires at 65, elects 18 months of COBRA and enrolls in Part B at the end of it has missed the window by ten months, will owe a penalty, and may have had claims denied along the way.
• Retiree coverage is not current employment coverage. It is a benefit from a job that has ended. Medicare expects to be primary, and most retiree plans are written assuming you have both Part A and Part B.
• Marketplace, VA-only and severance-continuation coverage each have their own rules and none of them is the 20-employee protection.
• Coverage from a spouse who has retired stops counting the day their employment does, even if the plan carries on for a while.

If you are in any of those four boxes, the safe assumption is that you should be enrolling at 65 rather than waiting, and the conversation is worth having before the coverage changes, not after.

Your eight-month window — and the much shorter one for drugs

When the work coverage does end, two clocks start on the same day and they run at different speeds.

Sources: Medicare.gov "Working past 65", "Avoid late enrollment penalties" and creditable-coverage guidance. Arizona has not adopted a Medigap birthday or anniversary rule.

That third row is the one nobody warns you about, because it is not a penalty and so it never appears on a penalty page. It is simply a door that closes six months after your Part B begins. If a Medicare Supplement is likely to be your destination — and for a lot of people who spend part of the year out of state, it is — the time to compare is inside that window. Medicare Advantage vs. Medigap lays out both routes.

What it costs to get the timing wrong

The IRMAA half of that catches high earners who retire mid-year and then find their first Medicare premium priced off the salary they no longer have. That is appealable — retirement is a recognized life-changing event on Form SSA-44 — and it is worth doing with your tax advisor rather than guessing. You can see where your income lands first, and the full explanation is here.

Three situations I actually see in Peoria

The rules above are national. How they land is local, and north Peoria produces a particular mix.

• The out-of-state remote employee. Still on a Michigan or Washington employer’s plan, living in 85383. The 20-employee protection follows the employer, not the state, so the delay is usually safe — but when the job ends, the doctors they have started seeing at Arrowhead or in Sun City are the ones that have to be checked against whatever comes next. Nobody’s Peoria network is decided in Michigan.
• The owner-operator. A small business in the older 85345 core or along Grand Avenue, eight or twelve employees, a plan that has worked fine for years. Under 20 employees means Medicare pays first at 65 whether or not they enrolled. This is the household I most want to catch early.
• The still-working spouse. One partner retired at 63 and is on the other’s active plan. Everything holds until the working spouse retires — and then both clocks start on the same day for both people, which is a busier eight months than anyone expects.

All three are why the Peoria service-area page exists, and why the useful first step is a calendar rather than a plan comparison. The enrollment timeline tool will build yours from your birthday and your coverage end date in about a minute.

What to do next, in order

1. Ask your benefits administrator the headcount question — 20 or more, or fewer than 20 — and get the answer in writing.
2. Ask for the creditable coverage notice for the plan’s drug benefit. Keep it with your tax records; you may need it years from now to fight a Part D penalty.
3. Decide the Part A question deliberately, not by default, especially if an HSA is still being funded.
4. Put the coverage end date on a calendar the day you know it, and count eight months forward for Part B and two for drugs.
5. If you already have Part A and are adding Part B, apply online and have the employer complete form CMS-L564 — that form is what proves you had qualifying coverage and keeps the penalty off.
6. Do not wait for COBRA to end. Ever. It is the single most common way this goes wrong.

If you would rather have somebody look at your actual situation — the employer’s size, the drug coverage, whether Part A helps or hurts this year, and what your options look like from a Peoria address — that is a short conversation, and it does not require you to be ready to buy anything. Call (602) 844-6002 or book a time. I am independent, the office is in Anthem — roughly 25 minutes from north Peoria, out the Carefree Highway and down Lake Pleasant Parkway — and plenty of clients do the whole thing by phone. If the answer is “keep what you have and call me in three years”, that is what you will hear.