Medicare Part D Eligibility and Enrollment Requirements

In this article...
  • How do you become eligible for a Medicare Part D prescription drug plan? When can you enroll? Learn about your options for Medicare drug coverage.

Medicare Part D is a type of private Medicare insurance plan that provides coverage for prescription drugs. These plans can be used alongside Original Medicare (Medicare Part A and Part B). In some cases, a Party D plan may be paired with a Medicare Advantage (Medicare Part C) plan if it doesn’t already include drug coverage.

Who Is Eligible for Medicare Part D?

If you are enrolled in either Medicare Part A or Medicare Part B (or both), you are eligible to enroll in a Medicare Part D plan. This includes Medicare beneficiaries who are age 65 and older as well as those who qualified for Medicare before age 65 because of a disability. 

In order to enroll in a particular Part D plan, you must live in that plan’s service area. 

You are also eligible to enroll in a Medicare Part D plan if you are enrolled in a Medicare Advantage plan that does not include prescription drug coverage. Most Medicare Advantage plans do cover prescription drugs. These are called Medicare Advantage Prescription Drug plans (MA-PD).

Anyone who is not currently enrolled in either Medicare Part A or Part B is not eligible to enroll in a Medicare Part D plan. 

If you do not live within a particular plan’s service area, you will not be eligible to enroll in that specific Part D plan, despite being eligible for Part D in general. You will have to find a different Part D plan that is available where you live. 

If you have a Medicare Advantage plan that already includes prescription drug coverage, you cannot enroll in a stand-alone Part D plan. In order to do so, you would have to disenroll from your Medicare Advantage plan and switch back to Original Medicare coverage.

When to Enroll in Medicare Part D

Just because you meet the eligibility requirements for Medicare Part D doesn’t mean you can run out and enroll in a plan at any time of the year. There are certain enrollment periods during which you can enroll in a Medicare Part D plan. 

  • The first time you may enroll (for beneficiaries who qualify for Medicare based on age) is during your Medicare Initial Enrollment Period (IEP). This enrollment period begins three months before you turn 65 years old, includes the month of your birthday and continues for three more months, for a total of seven months. You can enroll in Medicare Part A and Part B during this period, and you’ll also have the option to add a Medicare Part D plan or enroll in a Medicare Advantage plan. 

  • The Medicare Annual Enrollment Period (AEP) runs from Oct. 15 to Dec. 7 each year and presents a time for beneficiaries to enroll in, switch or drop Medicare Part D or Medicare Advantage plans. This enrollment period is also often referred to as the fall Medicare Open Enrollment Period.

  • If you missed your initial deadline to enroll in Original Medicare, you must wait to enroll during the General Enrollment Period which lasts from Jan. 1 to March 31 each year. If you sign up for Original Medicare at that time, you may then enroll in a Medicare Part D plan between April 1 and June 30.

  • If you qualify for a Special Enrollment Period, you may be able to enroll in a Medicare Part D plan at that time. 

Part D Extra Help Eligibility

In addition to being eligible for Medicare Part D, you may also qualify for Part D cost assistance.

Extra Help is a Medicare program that helps beneficiaries pay for Part D prescription drug costs, premiums, deductibles and copayments. 

There are also Drug Cost Assistance Programs and State Pharmaceutical Assistance Programs that partner with Medicare.