Understanding Your Health Insurance – Aug. 9, 2015: What is the Medicare Part D late enrollment penalty?AUGUST 9, 2015 LAST UPDATED: MONDAY, AUGUST 10, 2015, 12:16 AMBY IRENE & BETSY CARDSUBURBAN TRENDS PrintMedicare Part D is the prescription drug component to Medicare. If you enroll in a Part D plan after your 65th birthday, as you have been covered by group health insurance up to that time, you have a very good chance of receiving a letter stating that you will have a late enrollment penalty.What is the late enrollment penalty? It is an amount of money added to your Medicare Part D monthly premium. You may owe a late enrollment penalty if you go without Part D or creditable prescription drug coverage for any continuous period of 63 days or more after your initial enrollment period is over. Creditable coverage is coverage that is equal to or better than the benefits offered under Medicare Part D. If you have employer-sponsored coverage, it may or may not be creditable coverage. It is the employer’s responsibility to inform you each year if your coverage if considered creditable or not.