Medicare Part D late enrollment penalty calculator

How the penalty works

1. Count the full months between when you were first eligible and when you enrolled.
2. Multiply that count by 1% of the current national base beneficiary premium.
3. Round to the nearest 10 cents. That amount is added to your Part D premium.

The national base beneficiary premium is set by CMS each year, so the dollar amount of the penalty changes annually.

A worked example

How to avoid the penalty

• Enroll in Part D (or a Medicare Advantage plan with drug coverage) during your Initial Enrollment Period.
• If you keep employer drug coverage past 65, confirm in writing that it is creditable.
• Sign up for Part D within 63 days of losing creditable coverage.

Check your enrollment deadline by state

Frequently asked questions

How is the Part D late enrollment penalty calculated?

Medicare multiplies one percent of the national base beneficiary premium by the number of full months you went without creditable drug coverage after eligibility. The result is rounded to the nearest 10 cents and added to your Part D premium for as long as you have Part D.

What counts as creditable coverage?

Creditable coverage is drug coverage from an employer, union, TRICARE, VA, or another source that is expected to pay, on average, at least as much as standard Medicare Part D. Your plan must send you a creditable coverage notice each year.

Does the penalty ever go away?

Usually no. The penalty is permanent for as long as you stay enrolled in Part D. It does end if you qualify for Extra Help (the low-income subsidy), and certain limited situations allow a one-time reconsideration.

When am I first eligible to enroll in Part D?

Most people can first enroll during their seven-month Initial Enrollment Period around their 65th birthday. After that, the main window is the Annual Enrollment Period from October 15 to December 7 each year.