10% for every full year you could have had it
If you do not sign up for Part B when you are first eligible, your monthly premium may rise by 10% for each full 12-month period you could have had Part B and did not. You pay it for as long as you have Part B, which for most people means for life.
Medicare publishes a worked example: someone whose Initial Enrollment Period ended in December 2021 and who signed up in March 2024 pays a 20% penalty, because two full 12-month periods had passed.
One percent a month, and it keeps moving
The Part D penalty is 1% of the national base beneficiary premium for each full month you were eligible but had neither Part D nor other creditable drug coverage. The result is rounded to the nearest 10 cents and added to your monthly premium.
Because it is a percentage of a national figure rather than of your own plan premium, the penalty changes when that figure changes. The base was $38.99 in 2026 and is $41.33 in 2027, so the same penalty costs slightly more each year it rises.
Creditable coverage is the key phrase. Employer drug coverage that is at least as good as Part D counts, which is why keeping the letter your employer sends about creditable coverage matters.
The one with an end date
Most people get premium-free Part A and this never applies to them. If you have to buy Part A and do not sign up when first eligible, the premium may rise by 10%, and you pay the higher amount for twice the number of years you could have had Part A but did not.
So two years of delay means four years of the higher premium. Unlike Parts B and D, this one does eventually stop.
When no penalty applies
A Special Enrollment Period generally protects you. If you delayed Part B because you had coverage from current employment, signing up during the eight-month window after that employment or coverage ends usually avoids the penalty entirely.
Enrolling in a Medicare Savings Program can also remove a Part B penalty, and people who qualify for Extra Help do not pay the Part D penalty.
Frequently asked questions
How much is the Medicare Part B late enrollment penalty?
Your Part B premium may increase by 10% for each full 12-month period you could have had Part B but did not sign up, and you pay it for as long as you have Part B. A two-year delay means a 20% surcharge on the premium.
How is the Part D penalty calculated?
It is 1% of the national base beneficiary premium multiplied by the number of full months you went without creditable drug coverage, rounded to the nearest 10 cents. The base figure is $38.99 for 2026 and $41.33 for 2027.
Does the late enrollment penalty ever go away?
The Part B and Part D penalties last for as long as you have that coverage. The Part A penalty is different: you pay it for twice the number of years you delayed, and then it stops.
I had employer coverage. Do I still owe a penalty?
Usually not. Coverage from current employment generally gives you a Special Enrollment Period, and signing up within it avoids the Part B penalty. For Part D, employer drug coverage counts if it is creditable, which your employer must tell you in writing.
Sources
This guide explains officially published rules and figures. It is not an insurance quote and not an eligibility determination. Only HealthCare.gov, Medicare.gov, Social Security or the carrier can determine your eligibility and your actual price.
We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Not connected with or endorsed by the U.S. government or the federal Medicare program.
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