If you don’t enroll in a Part D prescription drug plan or Medicare Advantage plan with Part D coverage when first eligible, you may face the Part D late enrollment penalty. This penalty is added to your monthly Part D premium and remains permanently once incurred. You’ll be assessed this penalty if you go without Part D coverage or other creditable prescription drug coverage for 63 or more consecutive days after your Initial Enrollment Period ends.
The penalty amount depends on how long you went without coverage. It’s calculated by multiplying 1% of the national base beneficiary premium times the number of full uncovered months. For 2026, the national base beneficiary premium is $35.63, so each uncovered month costs you approximately 36 cents per month in penalties. The monthly penalty is rounded to the nearest 10 cents and added to your Part D premium.
The penalty takes effect immediately when you enroll in a Part D plan and continues for as long as you have Medicare prescription drug coverage. Since the national base beneficiary premium can change annually, your penalty amount may also increase each year, making early enrollment crucial to avoid these permanent costs.
