How the penalty works
- 10 percent per full year: for each full 12-month period you could have had Part B but did not sign up.
- Added to the premium, not charged once.
- Usually for life: it is charged for as long as you have Part B.
- Based on the standard premium, so it moves with the premium each year; higher incomes also pay the surcharge in Medicare costs 2026 on top.
What it costs in 2026
With the 2026 standard premium of $202.90, rounded to the nearest $0.10 as Medicare.gov does:
| Full years late | Penalty | Monthly Part B premium | Extra per year |
|---|---|---|---|
| 0 | 0% | $202.90 | $0.00 |
| 1 | 10% | $223.20 | $243.60 |
| 2 | 20% | $243.50 | $487.20 |
| 3 | 30% | $263.80 | $730.80 |
| 5 | 50% | $304.40 | $1,218.00 |
| 10 | 100% | $405.80 | $2,434.80 |
The 2-year row is Medicare.gov's own example: $202.90 plus $40.58 is $243.48, which becomes $243.50.
The enrollment windows
| Window | When | Penalty |
|---|---|---|
| Initial Enrollment Period | 7 months: from 3 months before the month you turn 65 to 3 months after it | None |
| Special Enrollment Period, job-based coverage | From the month after your Initial Enrollment Period while you have coverage through your or your spouse's job, until 8 months after that coverage or the job ends, whichever comes first | None |
| General Enrollment Period | January 1 to March 31 each year; coverage starts the month after you sign up | May apply |
Other Special Enrollment Periods cover, among others, losing Medicaid, a declared disaster or emergency, misleading information from a plan or employer, and release from incarceration.
Coverage that does not protect you
- COBRA or retiree coverage ending does not open a Special Enrollment Period; the employer coverage options are compared in COBRA explained.
- Marketplace coverage, whether you have it or lose it, does not either.
- Missing the 8-month window after work coverage ends leaves only the General Enrollment Period.
People who enroll in a Medicare Savings Program generally do not pay the Part B penalty. Part A has its own penalty for those who must buy it, 10 percent for twice the number of years you were late, and drug coverage has the 1 percent a month penalty in Medicare Part D explained. Your 6-month Medigap open enrollment also starts with Part B, which is one more reason the timing matters.
Frequently asked questions
How much is the Medicare Part B late enrollment penalty?
10 percent of the standard Part B premium for each full 12-month period you could have had Part B but did not sign up, per Medicare.gov. Waiting 2 full years means a 20 percent penalty: in 2026, $202.90 plus $40.58, or $243.50 a month after rounding.
Is the Part B penalty for life?
Usually. Medicare.gov says late enrollment penalties are added to the monthly premium, are not a one-time fee and are usually charged for as long as you have that coverage, which for most people means for life.
How do I avoid the Part B penalty?
Sign up during your 7-month Initial Enrollment Period around your 65th birthday, or later during a Special Enrollment Period, for example within 8 months after job-based coverage or the job ends, whichever comes first. Enrolling in a Medicare Savings Program also generally means no penalty.
Does COBRA or retiree coverage protect me from the penalty?
No. Medicare.gov lists the end of COBRA or retiree coverage, and having or losing Marketplace coverage, among the situations that do not qualify for a Special Enrollment Period.
What if I missed my enrollment window?
You can sign up during the General Enrollment Period from January 1 to March 31 each year; coverage starts the month after you sign up, and you may owe the penalty unless you qualify for a Special Enrollment Period.
Sources
- Medicare.gov: Avoid late enrollment penalties (penalties added to the monthly premium, usually for life; Part B: 10% for each full 12-month period, no penalty with a Special Enrollment Period or a Medicare Savings Program, the 2026 example of $202.90 plus $40.58, rounded to $243.50; Part A: 10% for twice the years; Part D: 1% a month)
- Medicare.gov: When does Medicare coverage start? (the 7-month Initial Enrollment Period, when Part B starts, the General Enrollment Period from January 1 to March 31, Special Enrollment Periods including 8 months after job-based coverage or employment ends, situations that do not qualify)
General information based on the sources above, not medical advice.