What Happens If You Enroll Late
Missing an enrollment window without another qualifying reason can lead to a late-enrollment penalty — and for two parts of Medicare, that penalty is permanent. Here's how each one works.
Part B Penalty
For each full 12-month period you were eligible for Part B but didn't enroll — and didn't have other creditable coverage, such as a large employer's group plan — the standard Part B premium increases by 10%. This penalty is added to the premium for as long as Part B coverage is kept, which for most people means permanently.
Try the Part B penalty calculator →Part D Penalty
If there's a continuous gap of 63 days or more without Part D drug coverage — or other creditable prescription drug coverage — after your Initial Enrollment Period ends, a penalty of roughly 1% of the "national base beneficiary premium" is added for every full month without coverage. Like the Part B penalty, this one is also generally permanent and is added to the Part D premium for as long as drug coverage is kept.
What About Part A?
Most people don't pay a premium for Part A at all, since it's usually earned through payroll taxes over a working career — so there's typically no late penalty to worry about. A penalty only applies to the small number of people who have to pay a Part A premium and don't enroll when first eligible.