Medicare Late Enrollment Penalty
June 22, 2026
The Medicare late enrollment penalty, explained.
Miss your enrollment window without other coverage and you can pay a surcharge for life. Here is how each penalty works and how to avoid it.
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What the penalty is
Medicare charges a late enrollment penalty when you do not sign up when you are first eligible and you do not have other qualifying ("creditable") coverage. The penalty is added to your monthly premium, and for Part B and Part D it usually lasts for as long as you have that coverage.
The fix is almost always to enroll during your Initial Enrollment Period — the seven-month window around your 65th birthday — or to keep creditable coverage and use a Special Enrollment Period later.
Part B late enrollment penalty
Your Part B premium goes up 10% for each full 12-month period you could have had Part B but did not sign up. Because Part B is medical coverage most people need, this penalty is the most common one.
It is not a one-time fee. The surcharge is added to your premium for as long as you have Part B, and it grows the longer you wait. If you delayed three years, that is roughly a 30% higher premium — permanently.
Part D late enrollment penalty
If you go 63 days or more without Part D drug coverage or other creditable prescription coverage after your Initial Enrollment Period, you can owe a Part D penalty. It is calculated as 1% of the "national base beneficiary premium" times the number of months you went without coverage, then added to your Part D premium for as long as you have a drug plan.
Even if you take no medications today, enrolling in a low-cost Part D plan on time protects you from this lifelong surcharge.
Part A penalty and how to avoid all three
Most people get premium-free Part A and never face a Part A penalty. If you have to buy Part A and enroll late, the premium can rise 10% for twice the number of years you delayed.
- Sign up during your Initial Enrollment Period around age 65.
- If you keep working, make sure your employer coverage is creditable and use a Special Enrollment Period when it ends.
- Keep proof of any creditable drug coverage so you are not charged a Part D penalty by mistake.
- Do not rely on COBRA or retiree-only plans as a reason to delay Part B — they often do not count.