The Part B late enrollment penalty: 10% for every year, for life
How the Part B penalty is calculated, what it costs at 2026 premium levels, who is exempt, and how the Special Enrollment Period works after employer coverage.
If you do not sign up for Part B when first eligible, and you do not have qualifying coverage from current employment, your Part B premium goes up by 10% for each full 12-month period you could have had Part B but did not. The surcharge lasts as long as you have Part B, usually for life.
The maths
Three years late adds $61 a month, or $730 a year, in 2026 terms. Ten years late doubles the premium.
Who avoids the penalty
- People covered by a group health plan based on current employment (their own or a spouse's). When that coverage or employment ends, they have an 8-month Special Enrollment Period to sign up for Part B without penalty.
- Some people with coverage that ended due to circumstances beyond their control, such as natural disasters or employer errors, under exceptional-condition SEPs.
COBRA and retiree coverage do not count as current-employment coverage for this purpose. Neither does Marketplace coverage. This is the most common mistake people make.
The General Enrollment Period
If you miss your IEP and do not qualify for a Special Enrollment Period, you can sign up during the General Enrollment Period, January 1 to March 31 each year. Coverage starts the month after you enroll, with the penalty applied.
Part D has its own penalty
Delaying drug coverage without creditable coverage triggers a separate penalty: 1% of the national base premium for each month without coverage. See the Part D penalty.
Questions people ask
How much is the Part B penalty?
10% of the standard premium for each full 12 months you were eligible but not enrolled.
Does COBRA count as creditable coverage for Part B?
No. Only coverage based on current employment avoids the penalty.
How long does the penalty last?
Usually for as long as you have Part B.
What is the Special Enrollment Period?
Eight months after employer coverage or employment ends to enroll in Part B without penalty.
Independent educational site. Not affiliated with or endorsed by the U.S. government, the federal Medicare program, or any insurance company. Figures are 2026 amounts published by CMS unless noted; check Medicare.gov for your situation.