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Medicare Part D Prescription Drug Coverage

This information is designed to help you decide whether to enroll in a Medicare Part D drug plan and how to decide which plan is best for you. To choose the right plan you have to look closely at your needs and the drugs you take.

What is the Medicare Part D drug benefit?

Medicare Part D is the prescription drug benefit offered to people who qualify for Medicare insurance. In other words, you must have Medicare Part A or Part B (or both) to join a Medicare Prescription Drug Plan.

Part D coverage may help you lower your prescription drug costs. It might also help protect you from higher costs in the future. It can also give you greater access to the drugs you need to stay well or treat an illness.

When you enroll in an approved Medicare Part D drug plan, you usually pay a monthly premium. You’re given a Medicare Part D plan ID card to use when you get prescriptions filled.

If you decide not to enroll in a Medicare drug plan when you are first eligible (able to join), you might have to pay a penalty when you enroll later, and every month after that for as long as you’re enrolled in Part D. If you have drug coverage through your current or former employer (or spouse's employer) you should find out if your coverage is good as, or better than, the coverage offered under Part D.

Each year, the plans vary in cost and which drugs are covered. Visit to use the plan finder to compare the available drug plans, find out whether the drugs you need are on the formularies, and learn about costs and any restrictions in coverage.

As a cancer patient, your annual drug costs may be high, so it is even more important that you look at all of the available plans to find the one that best meets your needs. Look carefully at the drugs each plan covers and how much you’ll have to pay (this is called cost sharing). Medicare has an online tool to help you choose.

The Medicare coverage gap (donut hole)

The coverage gap (also called the donut hole) starts when you reach a certain level of drug expense for the year. It’s the amount you must pay each year for your own prescription drugs, with some discounts. Once your total drug costs (what you and the plan pay for your prescriptions) reach a pre-set dollar amount for that year, you’re in the donut hole, where you pay more for drugs.

Once you are in the coverage gap, you will pay no more than 25% of your plan’s cost for brand name prescription drugs and a slightly higher cap on generic drugs. 

If your drug costs are high enough, you then hit catastrophic coverage. Medicare Part D plan will cover most of your drug costs and you will pay a small co-pay for covered drugs for the rest of that year.

Avoiding, minimizing, or delaying the coverage gap

There are some ways you can avoid or delay entering the gap, and save money on drug costs while in the gap:

  • You might be able to switch to generic drugs or other less costly drugs. Ask your doctor about generic alternatives that work just as well. Even though many cancer drugs do not have generics, the savings in non-cancer drugs may help a lot.
  • Keep using your Medicare drug plan card, even if your drug expenses fall in the coverage gap. Using your drug plan card ensures that you’ll get the drug plan’s discounted rates and that the money you spend counts toward your catastrophic coverage.
  • Look into Patient Drug Assistance Programs that may be offered by the company that makes the drug you take.

You can find out more about saving money by using mail-order pharmacies, generic, or less-expensive brand-name drugs online at

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

The Official U.S. Government Site for Medicare
Toll-free number:  1-800-MEDICARE (1-800-633-4227)

This is a federal government website managed by the U.S. Centers for Medicare and Medicaid Services.  It provides information about what Medicare covers, drug coverage (Part D), how to find a doctor or facility, and additional resources.

Centers for Medicare and Medicaid Services (CMS).  Drug coverage (Part D).  Accessed at on April 19, 2019.

Centers for Medicare and Medicaid Services (CMS). Costs in the coverage gap.  Accessed at on April 19, 2019.

Centers for Medicare and Medicaid Services (CMS).  Prescription drug assistance programs.  Accessed at on April 19, 2019.


Last Revised: May 13, 2019