2. What happens if I enroll late in Medicare Part D? Posted on September 11, 2017 at 12:11 pm.Written by advantage_admin You may face late enrollment penalties if, at any time during the 63 consecutive days following the end of an initial enrollment period, you fail to enroll in any of the following plans: Medicare Prescription Drug Benefit (Part D); a Medicare Advantage plan (such as a Health Maintenance Organization Plan [HMO] or a Medicare Preferred Provider Organization Plan [PPO]); any other Medicare health plan including prescription drug coverage; valid coverage for prescription drugs. Post navigation 1. What is Medicare Part D?3. Which plans cover Medicare Part D?