Medicare Late Enrollment Penalty Calculator
Delayed enrolling in Part B or Part D? Enter your dates and see an estimate of the penalty — monthly, yearly, and over time — plus whether creditable coverage protects you and how to challenge a penalty you don't think you owe.
The Short Answer
Medicare's Part B and Part D late enrollment penalties are permanent — they last as long as you have that coverage. But they only apply if you went without creditable coverage after your enrollment window closed. If you had qualifying employer, VA, or TRICARE coverage during the gap, you're usually protected and get a Special Enrollment Period. This tool estimates the penalty and shows you how to challenge one you don't believe you owe.
Important: This information is for general educational purposes only and is not a substitute for personalized Medicare counseling. Enrollment rules have many exceptions. Contact a licensed Medicare counselor or your State Health Insurance Assistance Program (SHIP) before making enrollment decisions. Find your local SHIP at shiphelp.org or call 1-800-MEDICARE (1-800-633-4227).
Editor's Recommendation
Before you accept a penalty, check for creditable coverage proof
The most common reason a Medicare late penalty is wrong is that the person actually had creditable coverage during the gap — through an employer, union, the VA, or TRICARE — and it wasn't counted. If that's you, gather the annual "Notice of Creditable Coverage" letters and request a reconsideration.
A free SHIP counselor does this routinely and knows exactly what documentation Social Security and Medicare want. There is never a reason to pay someone to appeal a Medicare penalty.
National SHIP directory: shiphelp.org · Social Security: 1-800-772-1213
How the Part B late enrollment penalty works
The Part B penalty adds 10% to your Part B premium for each full 12-month period you were eligible for Part B but did not sign up — and did not have creditable coverage. It is permanent: you pay the higher premium for as long as you have Part B, and because the penalty is a percentage of the base premium, the dollar amount grows over time as the base premium rises.
How the Part D late enrollment penalty works
The Part D penalty is 1% of the national base beneficiary premium for each month you went without creditable drug coverage after your enrollment window closed. In 2026 the national base premium is $38.99, so each month of delay adds roughly 39 cents per month to your drug plan premium — permanently. Twenty months without creditable coverage, for example, adds about $7.80 per month for life.
Part A is different — and rare
Most people never owe a Part A penalty because they qualify for premium-free Part A through 40 quarters (about 10 years) of Medicare-taxed work. If you do have to buy Part A and enroll late, the penalty is 10% added to the Part A premium — but only for twice the number of years you delayed, then it ends. It is not permanent like the Part B and Part D penalties.
Creditable coverage and Special Enrollment Periods
You are protected from these penalties while you have creditable coverage. For Part B, that generally means active employer coverage from an employer with 20 or more employees (yours or your spouse's). For Part D, it means drug coverage expected to pay, on average, at least as much as Medicare's standard drug coverage — employer plans, TRICARE, VA, and most Medicaid plans qualify. When that coverage ends, you usually get a Special Enrollment Period to enroll without any penalty. Keep the annual creditable-coverage notices your plan sends you.
Frequently Asked Questions About Medicare Penalties
The Part B penalty adds 10% to your Part B premium for each full 12-month period you were eligible but did not enroll and did not have creditable coverage. It is permanent — you pay it for as long as you have Part B — and it rises over time as the base premium rises.
The Part D penalty is 1% of the national base beneficiary premium for each month you went without creditable drug coverage after your enrollment window, rounded to the nearest 10 cents and added to your drug plan premium permanently. In 2026 the national base premium is $38.99.
Yes. If you had creditable coverage — such as an employer group plan with 20 or more employees, VA, or TRICARE — during the gap, penalty accrual is suspended and you usually get a Special Enrollment Period to enroll without penalty. Keep proof of that coverage in case Social Security asks for it.
Yes. You can request a reconsideration if you believe you had creditable coverage during the gap or the penalty was calculated incorrectly. Gather your creditable-coverage notices and contact Social Security or Medicare. A free SHIP counselor can help you file the reconsideration — you never need to pay anyone to appeal.