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By YourBest Editorial Team · Updated October 17, 2026 · How we rank

Calculator · Medicare.gov rules

Medicare Late Enrollment Penalty Calculator: Part B and Part D

Sign up for Part B or Part D late and Medicare adds a penalty to your premium, usually for as long as you have that coverage. See what a gap would cost you per month, per year and over ten years.

10%Part B penalty for each full 12 months you could have had it

1%Part D penalty per month without creditable drug coverage

63 daysgap in drug coverage that starts the Part D penalty

Estimate your penalty

Months without Part BMonths you could have had Part B but didn’t, after your Initial Enrollment Period, not counting months with job-based coverage from current work

Months without drug coverageFull months after your Initial Enrollment Period with no Part D or other creditable drug coverage

Premium yearPenalties are recalculated each year

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—Part B penalty per month

—Part D penalty per month

—Over 10 years at this year’s amounts

Part B uses the 2026 standard premium ($202.90) until CMS announces the 2027 amount. Part D uses the national base beneficiary premium: $38.99 for 2026 and $41.33 for 2027. Real penalties rise when those amounts rise.

How the Part B penalty works

If you don’t sign up for Part B when you’re first eligible, your monthly premium may go up 10% for each full 12-month period you could have had it but didn’t. You usually pay the penalty for as long as you have Part B. The penalty is a percentage of the standard premium, so it grows when the premium does.

You generally won’t pay a penalty if you delayed Part B because you (or your spouse) were covered by a group health plan based on current employment, and you sign up within 8 months of that coverage or work ending. COBRA and retiree coverage don’t count as current employment.

How the Part D penalty works

If you go 63 days or more in a row without Part D or other creditable drug coverage after your Initial Enrollment Period ends, Medicare adds a penalty of 1% of the national base beneficiary premium for each full month you were uncovered. It is rounded to the nearest 10 cents and added to your monthly Part D premium for as long as you have Part D. People who get Extra Help don’t pay it.

Questions

Is the Medicare late enrollment penalty permanent?

For Part B and Part D, usually yes: you pay it for as long as you have that coverage. The Part A premium penalty (for people who buy Part A) lasts twice the number of years you could have had it but didn’t.

Does employer coverage protect me from the penalty?

For Part B, coverage from a group health plan based on your or your spouse’s current work does, if you enroll within 8 months after it ends. For Part D, any drug coverage that is at least as good as Medicare’s (creditable) does; your plan sends a yearly notice saying whether it is.

Can I appeal a late enrollment penalty?

Yes. For Part D you can ask for a reconsideration, for example if you had creditable coverage. Medicare.gov explains how.

Sources

Medicare.gov, “Avoid late enrollment penalties” — medicare.gov. Part A, B and D penalty rules, checked October 17, 2026.
CMS, Part D national base beneficiary premium — cms.gov fact sheet.
CMS, 2026 Part B premium — cms.gov fact sheet.

Educational estimate. Medicare and Social Security decide any penalty. · Advertiser disclosure