The Medicare Part B Late Enrollment Penalty, Explained

Here's the rule in one line: for every full 12 months you could have had Part B but didn't, your Part B premium goes up 10%. And in most cases, you pay it for as long as you have Part B.

Not one year. Not five. As long as you have Part B.

That's why I'd rather spend ten minutes on this now than have you pay for it every month for twenty years.

The mental model: a late fee that never expires

Most late fees are one-time. You pay it, you're done.

The Part B penalty isn't like that. It's a percentage stapled to your premium. As the standard premium changes each year, the penalty moves with it.

So think of it as a permanent surcharge, not a fine.

The analogy: a library book with a daily fine

Remember library fines? Every day the book was late, the fine grew.

The Part B penalty grows the same way, just in yearly chunks. One full year late, 10%. Two full years, 20%. Three, 30%. The longer the book sits on your shelf, the bigger the bill.

Except this library keeps charging you after you return the book.

The math, with real numbers

Medicare's own example uses 2026 figures. The standard Part B premium in 2026 is $202.90 a month.

Say you waited 2 full years (24 months) to sign up and didn't qualify for a Special Enrollment Period:

• 20% penalty (10% x 2 full years)
• $202.90 x 20% = $40.58
• Your 2026 Part B premium: about $243.50 a month

The 2027 Part B premium hasn't been announced yet. Medicare announces it each fall. Whatever it is, your penalty percentage applies to it.

A note on "full" years: the penalty counts full 12-month periods. Medicare says you won't pay a penalty if you sign up before the first full 12-month period ends.

Who usually gets hit

From what I see, it's rarely people who ignored Medicare on purpose. It's people who thought they were covered:

• Folks on COBRA. COBRA doesn't count as coverage from current work. The clock is running.
• Folks with retiree coverage. Same deal. Not current work.
• Folks at small employers. With fewer than 20 employees, Medicare usually pays first. Waiting on Part B can backfire.
• Veterans who only use VA care. VA health care doesn't protect you from the Part B penalty. The VA itself encourages vets to sign up for Medicare when eligible.
• People with individual Marketplace plans. Those aren't job-based group coverage.

How to avoid it

You generally won't owe the penalty if you:

1. Sign up during your Initial Enrollment Period. That's the 7 months around your 65th birthday: 3 months before, your birthday month, and 3 months after.
2. Qualify for a Special Enrollment Period. The common one: you (or your spouse) are still working and covered by that job's group plan. You then have 8 months after the job or coverage ends, whichever comes first. My article on working past 65 walks through it.
3. Enroll in a Medicare Savings Program. Medicare says you generally won't pay a Part B penalty if you're in one. More on those in my piece on Extra Help and Medicare Savings Programs.

Already missed it? Here's what happens

If you missed your window and don't qualify for an SEP, you can sign up during the General Enrollment Period, January 1 to March 31. Coverage starts the month after you sign up.

That means two costs:

• A possible gap in coverage until you can sign up.
• The penalty on top of your premium.

If you're in that spot, don't wait another year. Each additional full year adds another 10%.

Don't forget the Part D penalty

Drug coverage has its own late penalty. Say you go 63 days or more in a row without Part D or other creditable drug coverage after your first chance to enroll. Then you can owe a penalty. It's 1% of the national base premium for each full month you went without. It's also added for as long as you have drug coverage.

Different rule. Same lesson. Our Part D page has more.

Things I'd do (and never do)

1. I'd write my Initial Enrollment Period dates on the fridge. 3 months before, birthday month, 3 months after.
2. I'd get my employer's size in writing before deciding to wait on Part B.
3. I'd sign up for Part B before COBRA starts, not after it ends.
4. I'd never assume VA care or a Marketplace plan lets me skip Part B without checking first.
5. I'd never wait "just one more year." That year costs 10%, possibly for life.

Not sure if you're on the clock?

Tell us your birthday, your coverage, and your work situation. We'll tell you plainly whether you need Part B now and what deadline you're facing.

Call (417) 633-7200, or visit our Joplin office or Springfield office. We have more ways to reach us on our FAQ page.

Ten minutes now beats a penalty forever.

— Matt

Frequently asked questions

How much is the Part B late enrollment penalty?

It's 10% of the standard Part B premium for each full 12-month period you could have had Part B but didn't. In most cases, you pay it for as long as you have Part B.

Does the Part B penalty ever go away?

In most cases, no. It's added to your premium each month for as long as you have Part B. Medicare notes you generally won't pay it if you qualify for a Special Enrollment Period or enroll in a Medicare Savings Program.

Does COBRA protect me from the Part B penalty?

No. COBRA isn't coverage based on current work. Your 8-month Special Enrollment Period starts when you stop working, even if you take COBRA.

When can I sign up for Part B if I missed my first chance?

During the General Enrollment Period, January 1 to March 31 each year. Coverage starts the month after you sign up. You may owe a penalty unless you qualify for a Special Enrollment Period.

Do I owe a penalty if I have VA health care?

VA health care doesn't prevent the Part B penalty. If you skip Part B and sign up later without a Special Enrollment Period, the penalty can apply.