Medicare Part D – prescription drug coverage

Understanding prescription drug plans (PDPs) and Medicare advantage prescription drug plans (MAPDs)

  • September 17, 2018

How does Medicare Part D work?

  • For Original Medicare enrollees, the only source of prescription drug plans is through private insurance companies.
  • Most Medicare Advantage plans include prescription drug coverage.
  • You can also purchase a stand-alone prescription drug plan if your MA plan doesn’t include prescriptions.
  • Your first opportunity to enroll in Part D is when you’re initially eligible for Medicare.
  • You have the option of selecting an Advantage plan and using that in place of Medicare A, B, and D.
  • In most cases, enrollment outside of your initial enrollment period is limited to an annual enrollment period.
  • If you don’t enroll in prescription drug coverage during your initial open enrollment and then enroll later during general open enrollment, a late enrollment penalty will be added to your premium.
  • In 2017, more than 42 million Medicare beneficiaries had prescription drug coverage through Medicare Part D. About 60 percent of them had a stand-alone prescription drug plan (PDP) in conjunction with Original Medicare, while the other 40 percent had a Medicare Advantage prescription drug plan (MAPD). For those enrolled in Original Medicare, the only source of PDPs is through private insurance companies, as Medicare A and B don’t cover outpatient prescriptions. Most Medicare Advantage plans do include prescription drug coverage, although in some cases you can purchase a stand-alone PDP if your Medicare Advantage plan doesn’t include prescriptions.

    When and how do I enroll in Medicare Part D?

    The first opportunity for enrollment is when you’re initially eligible for Medicare – during the seven-month period beginning three months before the month you turn 65. If you enroll prior to the month you turn 65, your prescription drug coverage will begin the first of the month you turn 65. If you enroll during the month you turn 65 or one of the three following months, your prescription coverage effective date will be delayed — it will not be retroactive to the month you turned 65.

    If you enrolled in Medicare due to a disability, you may enroll during a seven-month window beginning three months prior to your 25th month of disability. If you enroll in the three months prior to your 25th month of disability, your coverage will begin the first day of the 25th month. If you enroll during the 25th, 26th, 27th, or 28th month of disability, your coverage will begin the first of the month after you enroll.

    Here’s more information on how to pick a prescription drug plan.

    In both of these cases – whether you’re turning 65 or are eligible for Medicare because of a disability — you have the option of selecting a Medicare Advantage plan that includes prescription drug coverage, and using that in place of Medicare A, B, and D (note that this is generally not the case if you have end-stage renal disease). The enrollment periods and rules are the same as those described above for stand-alone Medicare Part D plans.

    After you’ve chosen from the various PDP offerings, you can enroll by:

    • calling 1-800-MEDICARE to locate PDPs in your area
    • logging in to Medicare’s Prescription Drug Plan Enrollment Center
    • filling out the paperwork sent by mail from Medicare, or
    • calling the private insurer with the specific PDP you want to join.
    • calling 1-855-593-5633 to talk with one of medicareresoures.org’s partners, where a licensed agent can assist you.

    Once you apply for Plan D, it generally takes five weeks for your membership card to arrive. During that time, if you need prescription medications, most pharmacies will accept the initial letter you received from Medicare acknowledging your upcoming membership, or an enrollment confirmation number.

    In most cases, enrollment outside of your initial enrollment period is limited to an annual enrollment period between October 15 and December 7, with coverage starting January 1 of the following year. During this time, you can switch to a new PDP or Medicare Advantage plan, and coverage is guaranteed issue. The new plan will automatically replace the old one, so you don’t need to do anything other than enroll in the new plan.

    If you are enrolled in a Medicare Advantage plan and want to switch to Original Medicare, you can do so either during the fall open enrollment period (October 15 – December 7) or during the Medicare Advantage open enrollment period (January 1 – March 31). If you do so, you’ll also have the option to purchase a Part D plan at the same time, so that you’ll have prescription coverage to go along with your Original Medicare coverage.

    If you didn’t enroll in prescription drug coverage – either through a PDP or a Medicare Advantage plan – during your initial open enrollment window and then you enroll during a general open enrollment period in a future year, there’s a late enrollment penalty that will be added to your premium (the late enrollment penalty does not apply if you delayed your Part D enrollment because you maintained creditable drug coverage from another source — like an employer-sponsored health insurance plan).

    The Part D late enrollment penalty would also apply if you drop your prescription coverage for more than 63 days and then re-enroll during a general open enrollment period. It’s important to maintain continuous drug coverage from the time you’re first eligible, both to protect against significant prescription costs, and also to avoid higher premium when you ultimately re-enroll.

    What will I pay for part D coverage?

    In 2018, the average stand-alone prescription drug plan premium is $43.48/month, including both basic and enhanced Part D plans. But the plans are issued by private insurers, and there’s significant variation in terms of the benefits, the formularies (covered drug lists) and the pricing. Among the ten Part D plans with the largest enrollment, average premiums range from $20.21/month to $83.68/month.

    High-income enrollees (those with income above $85,000 for a single individual or $170,000 for a married couple) pay extra for their Part D coverage. In 2019, the additional premiums (which are added to the regular amount that the Part D insurer charges) are projected to range from $13.20/month to $82.90/month (see Table V.E4 in the Medicare Trustees’ Report).

    In addition to the premiums, you’ll pay a copay (fixed cost) or coinsurance (a percentage of the cost of your medications) for drugs. The “donut hole” (coverage gap) in Part D plans has been steadily closing over the last few years, thanks to the Affordable Care Act. It will be fully closed by 2020. And it’s closing a year early, in 2019, for brand name drugs, thanks to the Bipartisan Budget Act of 2018. Enrollees with standard Part D coverage in 2019 will pay 25 percent of the cost of brand name drugs while in the donut hole, which is the same percentage they pay before entering the donut hole (originally, enrollees were scheduled to pay 30 percent in 2019, with the drop to 25 percent coming in 2020). Enrollees in standard plans will pay 37 percent of the cost of generic drugs while in the donut hole in 2019, and that will drop to 25 percent in 2020.


    Stuck in Medicare’s ‘donut hole?’ A prescription discount card could help lower your costs.


    Your out-of-pocket costs will depend on the plan you choose, based on your individual medical needs. Be sure to look beyond the plan premium and consider all costs. You can use Medicare’s plan finder tool to help you select the best drug plan to meet your needs. This is a process that you’ll need to repeat each year during open enrollment, as drug formularies (covered drug lists) change along with premiums from one year to the next.

    Once you select a PDP, there are four ways to pay the premium:

    • deducted from your personal account;
    • charged to credit or debit card;
    • billed monthly; or
    • deducted from your Social Security check (You’ll contact your PDP issuer to set this up.)