Your job just ended and you are past 65. Here is your Medicare deadline.

Four things to do this week

This page is not legal, tax, medical or financial advice. It lays out the 2026 rules so you can check your own case fast.

1. Write down the month your job ends. Then write down the month your work health plan ends. Circle the one that comes first.
2. Count eight months from the circled month. That is the last month to sign up for Part B with no penalty.
3. Ask HR two things. How many people does the company employ? And does the plan pay first or second once you are 65?
4. Find the letter that says your drug coverage was creditable. That word means at least as good as Medicare's. Put it somewhere you can find in five years.

That is the fix. The rest of this page explains why each step matters.

COBRA looks like your old plan, and that is the trap

COBRA keeps the same card and the same doctors. So it feels like nothing changed.

Medicare sees it another way. Its working past 65 page says it plainly: COBRA coverage doesn't extend your limited time to sign up for Medicare.

Run it out. You leave your job and take eighteen months of COBRA. When it ends, you sign up for Medicare. But your eight months started back when the job ended. They closed ten months ago.

Retiree coverage from an old employer works the same way. Neither one is based on current work, and current work is what holds the window open.

If the company had fewer than 20 people

Here is a rule most people never hear. At a company with 20 or more workers, the work plan pays first. At a smaller one, Medicare pays first.

So if Medicare is meant to pay first and you never signed up, nobody pays first. Medicare's who pays first page warns that your job-based coverage might not pay if you don't have both Part A and Part B.

You can pay a premium every month and still have a hole. Write down who at HR told you the size of the company, and the date.

How to sign up for Part B when the job ends

Knowing the deadline is half of it. Here is how the signup itself works, from the current Part B form.

1. Get two forms. The CMS-40B is your request for Part B. It is for people who already have Part A. The CMS-L564, Request for Employment Information, is filled in by your employer to show you had job-based coverage. The 40B tells you to have your employer complete it and send it back with your application.
2. Write in the dates. The 40B asks when you, or your spouse, worked for the employer that gave you coverage, and when that coverage started and ended.
3. Pick a start date. If you sign up while you still have the job-based plan, or in the first full month after it ends, you can choose when Part B starts: the first day of the month you sign up, or the first day of any of the three months after.
4. Send it to Social Security. Mail or fax both forms to your local Social Security office. Medicare's sign-up page says you can also sign up online through Social Security, which it calls the easiest way.

The safest plan is to send the forms before your work plan ends. Then you can set Part B to start the day after it stops, with no gap.

If you do not have Part A yet, do not use the 40B. Contact Social Security to apply for Medicare first.

Two more deadlines that come with the job ending

Your drug coverage. You will not owe the Part D late penalty as long as you do not go more than 63 days in a row without creditable drug coverage. That clock starts when your job's drug coverage ends, so pick a drug plan in time.

A health savings account. If you have an HSA, Medicare's working past 65 page says you and your employer should stop putting money in 6 months before you retire. That helps you avoid a tax penalty. Ask a tax adviser how it fits your dates.

What late costs, in 2026 dollars

The Part B standard premium is $202.90 a month in 2026. Two full years late adds 20 percent on top. Twenty-three months late is one full twelve-month period, so 10 percent, not 20.

The drug penalty is smaller and it never stops. It starts after a gap of 63 days in a row. Two years with no creditable drug coverage is 24 months, so about $9.40 a month in 2026, worked out again each year. You can owe it even if you never had a drug plan. The Part D penalty page gives the full rule.

There was a cake, and nobody mentioned the clock

Maybe there was a card in the break room. Maybe the job ended without asking you. Either way, you went home and that was the whole ceremony.

Nobody put the deadline in the card. It is quiet and it is exact. It does not care if you feel ready.

If you want someone to look at your own dates for free, your State Health Insurance Assistance Program does that. Medicare describes SHIPs as not connected to any insurance company or health plan.

The rest of this calendar is in one book

This is the problem The Year You Retire was written for. Nancy Whitaker's book puts the Medicare clock first because it is the one with teeth.

The Window That Closes walks through the seven-month window around your 65th birthday, the eight-month window after work, the COBRA trap, the 20-worker rule and the 2023 change to start dates. It also lists what plan sellers are not allowed to do when they call you.

Your First Year Pages turns all of it into dates on one page, so the month you circled today does not live only in your head.

What we like is that every rule in the book comes with its source and its year. When a friend tells you about a gap she sat through in 2019, you can check whether that rule still exists. Since 2023, it mostly does not.