Calculator
Late enrollment penalty calculator
Estimate the Part B and Part D penalties for signing up late. Both are added to your premium for as long as you have the coverage, which is why the deadlines matter.
Part B penalty
Part D penalty
Estimates only. Social Security and your drug plan make the official calculation, and you can ask for a reconsideration if you think a penalty is wrong.
Frequently asked questions
Your Part B premium goes up 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. In 2026 the standard premium is $202.90, so a 20% penalty adds about $40.58 a month at 2026 rates.
Medicare multiplies 1% of the national base beneficiary premium by the number of full months you went without Part D or other creditable drug coverage after a gap of 63 days or more. The 2027 base premium is $41.33. The result is rounded to the nearest 10 cents and added to your monthly premium.
Usually, yes. If you had group health coverage from current employment, yours or your spouse’s, you can sign up for Part B during the 8-month Special Enrollment Period without a penalty. For Part D, employer drug coverage counts if it was creditable, which your plan should tell you in a yearly notice.
You can ask Social Security (Part B) or your drug plan (Part D) to reconsider if you believe the penalty is wrong, for example because you had creditable coverage. People who qualify for Extra Help do not pay a Part D penalty, and enrolling in a Medicare Savings Program can remove the Part B penalty.
Related guides
Learn · 6 min readPart B and Part D Late Enrollment Penalties, With Worked ExamplesHow the Part B, Part D and Part A late penalties are calculated, with worked 2026 and 2027 examples, the rounding rules, and the exceptions that avoid them.Read
Learn · 6 min readMedicare Part B: Coverage, Premium, Deductible and IRMAA (2026)Part B in 2026: the $202.90 premium, $283 deductible, 20% coinsurance, IRMAA surcharges, how the bill works, and what the 2027 premium will be.Read
Learn · 5 min readWorking Past 65: When You Can Delay Medicare (the 20-Employee Rule)Still working at 65? How the 20-employee rule decides who pays first, when you can safely delay Part B, what COBRA changes, and how to sign up when you retire.Read
Compare · 5 min readCOBRA vs Medicare at 65COBRA vs Medicare at 65: why COBRA pays second, why it does not stop the Part B penalty, the 8-month deadline, 2026 costs, and when COBRA still makes sense.Read
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