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Medicare Part D Late Enrollment Penalty Calculator
Estimate the monthly penalty added to your Part D premium if you went without creditable prescription drug coverage after becoming eligible.
Exclude your Initial Enrollment Period, partial months, and months with creditable coverage. This estimate uses the 2026 premium basis, not 2027.
Confirm penalty conditions to see a 2026 estimate.
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How is the Medicare Part D late enrollment penalty calculated?
Medicare multiplies 1% of the national base beneficiary premium ($38.99 in 2026) by the number of full uncovered months you went without Part D or other creditable prescription drug coverage after your Initial Enrollment Period, then rounds to the nearest $0.10 and adds it to your monthly Part D premium.
Does the Part D penalty go away eventually?
You generally pay the penalty for as long as you have Medicare drug coverage. If you receive Extra Help, you do not pay a Part D late enrollment penalty. The national base beneficiary premium changes annually, so the penalty amount can change.
What counts as creditable prescription drug coverage?
Creditable coverage is drug coverage expected to pay, on average, at least as much as Medicare's standard Part D coverage — common examples include many employer or union plans, VA drug benefits, and TRICARE. Your plan administrator can confirm in writing whether your coverage was creditable.
2026 penalty basis. Source: Medicare drug coverage costs.