Medicare Part B Late Enrollment Penalty Calculator
| Years late | Premium at $202.90 | Extra per year |
|---|---|---|
| 1 | $223.20 | $243.60 |
| 2 | $243.50 | $487.20 |
| 5 | $304.40 | $1,218.00 |
| 10 | $405.80 | $2,434.80 |
The Part B penalty works differently from every other Medicare penalty: it is not per month, it is per year. Every full 12 months you could have had Part B but didn't adds a permanent 10% to whatever premium you are paying, for as long as you have Part B. Two years late means 20% more every month, forever - on the 2026 standard premium of $202.90 that is the difference between $202.90 and $243.50 a month, and the gap widens as the base premium rises.
Two details trip people up. First, only full 12-month periods count - 17 months late is one penalty year, not two. Second, the penalty can be waived entirely, not just reduced: if you had group health coverage through your or a spouse's employer and enroll within 8 months of it ending, that Special Enrollment Period resets the clock, and a Medicare Savings Program waiver does the same. The penalty math above applies only to the months outside those windows.
How to use
- Count full 12-month blocks between your Initial Enrollment Period ending and when you actually signed up - partial years do not add penalty years.
- Start from your premium base: $202.90 is the 2026 standard amount; higher-income beneficiaries use their IRMAA-adjusted base instead.
- Read the monthly bill with penalty, then check the escape-hatch list - most penalties come from missed SEPs, not from waiting on purpose.
Frequently asked questions
How is the Part B penalty different from the Part D penalty?
Scale and clock: Part B adds 10% for each full 12 months late, while Part D adds 1% for each uncovered month - about 12% a year if you never had drug coverage. Part B's penalty is also calculated as a percentage of whatever premium you pay, so it grows every time the base grows.
Does the Part B penalty ever go away?
No - it stays for as long as you have Part B, and it is recalculated upward as the standard premium rises. The only people who escape it are those who qualify back: a Special Enrollment Period through employer coverage or a Medicare Savings Program can waive it before it starts.
I kept working past 65 with employer coverage - do I owe the penalty?
Almost certainly not, as long as the coverage was through your own or a spouse's current employer and you enrolled in Part B within 8 months of that job or coverage ending. That is the Special Enrollment Period, and it is the single most common penalty waiver - the penalties mostly hit people who retired without knowing the 8-month deadline exists.
Is the penalty the same for high earners?
The 10% per year applies on top of whatever premium tier you are in, so high earners pay the same percentage penalty on a bigger base - and IRMAA income surcharges stack separately on top of both. The calculator above uses the standard premium; substitute your own base if IRMAA applies to you.
When exactly does Part B enrollment start?
The Initial Enrollment Period runs seven months around your 65th birthday - three months before, the month of, and three months after. Miss it with no employer coverage in place and every full year afterward compounds the penalty at 10%.