The individual most likely to be eligible to enroll in a Medicare Part D plan is any person who is enrolled in Medicare Part A and/or Part B and lives in a Part D plan’s service area.

In typical multiple‑choice questions, the best answer is usually something like:

  • “A 66‑year‑old enrolled in Medicare Part A”
  • “A person under 65 who has Medicare due to disability”
  • “An individual with ESRD or ALS who already has Medicare coverage”

All of these are eligible because once you qualify for Medicare (by age 65 or by disability/ESRD/ALS) and are enrolled in Part A and/or Part B, you are also eligible to enroll in a Part D prescription drug plan , as long as there is a plan offered where you live.

So, if your options include someone who already has Medicare Part A and/or Part B , that person is the one most likely to be eligible for a Part D plan.

Information gathered from public forums or data available on the internet and portrayed here.