The Medicare Part D late enrollment penalty is a permanent surcharge added to your monthly Part D premium if you do not enroll in a Medicare Part D prescription drug plan when you are first eligible, unless you have other creditable prescription drug coverage. The penalty is calculated as 1% of the national base beneficiary premium for each full month you were eligible for Part D but did not enroll and did not have creditable drug coverage. For example, in 2025, the national base beneficiary premium is $36.78, so the penalty is 1% of this amount multiplied by the number of uncovered months, rounded to the nearest 10 cents. If you had a 14-month gap without coverage, your penalty would be 14% of $36.78, which is about $5.20 added to your monthly premium. This penalty lasts for as long as you have Medicare Part D, even if you switch plans. You can avoid the penalty if you qualify for Extra Help or have continuous creditable drug coverage comparable to Medicare Part D. If you disagree with the penalty, you have the right to file an appeal with Medicare.
