Clear Money Guide
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Updated August 1, 2026. Quick answer: the Part B late-enrollment penalty is 10% of the standard premium for every full 12-month period you could have enrolled and did not, and for most people it is permanent. The 2026 standard premium is $202.90 a month, so three years late costs $60.90 a month on top — $730.80 a year, $14,616.00 over twenty years of Medicare. The penalty counts only full years, which is why the eleventh month and the thirteenth month are worlds apart.
The calculator
Who actually gets hit
Not the people who forget. The people who were covered by something that felt like enough. The Special Enrollment Period for job-based coverage runs 8 months from the month the employment or the coverage ends, whichever comes first — and the two exclusions catch most of the casualties:
“COBRA isn’t considered group health plan coverage. Getting COBRA doesn’t change when this Special Enrollment Period ends.”
Retiree coverage is the other one. Losing it is explicitly listed among the situations that do not qualify for a Special Enrollment Period. So a person who retires at 65 with retiree medical, and treats it as active coverage, is accruing penalty months while holding an insurance card.
If you have already missed it
The General Enrollment Period runs January 1 to March 31, and coverage now begins the first day of the month after you sign up. That last part changed in 2023 and a great deal of published advice still says your coverage will not start until the following July. It is worth checking the date on anything you read about this — the old rule could leave someone uninsured for half a year, and the current one does not.
The arithmetic, in the open
Full years late × 10% × $202.90, added to the standard premium, and the total rounded to the nearest ten cents. Medicare publishes a worked example at 24 months: 20% penalty, a total of $243.50 a month. This calculator reproduces that figure exactly, which is the check that it implements the published rule rather than an approximation of it.
Coverage timing is one piece of the retirement decision
A penalty figure tells you what a timing choice costs, not how that choice sits next to the accounts, the income you plan to report and the years ahead, and an adviser can look at those together with you.
Before you start, what actually happens. The form is run by Kapitalwise, our advisor-matching partner. Kapitalwise sends your details to advisers who pay for the introduction, so expect calls and texts. Clear Money Guide is paid when you submit the form, whether or not you ever hire anyone. This is free to you and there is no obligation to hire anyone.
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Where this sits
The penalty is one of three Medicare costs that are decided years before you see them. The other two: the Part D penalty, which works on a different formula and catches people who had no drug coverage because they took no drugs, and IRMAA, which prices your premium off your income from two years earlier.
If you are still working, the enrol-or-delay decision turns on one number that has nothing to do with you: how many people your employer has. And for the dates themselves, your enrolment window.
2026 standard premium and deductible from the CMS Federal Register notice CMS-8091-N; penalty rule and worked example from medicare.gov. Both read August 1, 2026. Figures change annually. General information, not advice.
Military service changes two of these rules: prior active service can be bought into a FERS annuity for 3% of the pay you earned then — usually requiring you to waive military retired pay, though reserve retirees are excepted — and at 65 TRICARE requires Medicare Part B or it ends.
If either spouse is not a US citizen, one default fails silently: there is no unlimited marital deduction for a non-citizen spouse — the statute denies it outright, and most plans are drafted assuming otherwise. Living abroad changes the benefits side too: Social Security usually follows you and Medicare never does.
Retirees abroad face this penalty with no special enrolment period to escape it — the keep-or-drop decision.
See Read the adviser-hiring guide for more on this.