Skip to navigation Skip to content

When and How to Enroll in Medicare Prescription Drug Plans


In this article

When to enroll

Everyone who becomes eligible for Medicare has a seven month Initial Enrollment Period to sign up for Original Medicare or a Medicare Advantage Plan, as well as the prescription drug plan of their choice. To avoid a lifetime penalty for late enrollment in a Medicare prescription drug plan, make sure you enroll during your Initial Enrollment Period which starts three months before the month you are first eligible and ends three months after the month you are first eligible..

If you have creditable coverage (other prescription coverage as good as Medicare Part D coverage) or if you would like to delay enrollment in Medicare Part D for another reason, contact the Social Security Administration to confirm that you will not be penalized for late enrollment if you later choose to enroll in Part D.

How to enroll

There are several ways to enroll in the prescription drug plan of your choice:

  • online through Medicare’s website
  • by calling 1-800-MEDICARE (1-800-633-4227)
  • or by calling the plan directly

After you have enrolled, you will receive a notice verifying that your application has been received, or you can print one if you enroll online. Keep this until you receive a wallet card proving you are enrolled in your prescription drug plan. You will need to show that to your pharmacist when you fill your prescriptions.

Rules for enrolling

It is important to pay attention to the rules for enrolling or switching prescription drug plans because they are very limited for most people. All prescription drug plans must notify their enrollees in October of the changes to the costs or formularies they plan to make for the next year. It is very important to review your drug plan every year and switch if needed. All drug plan changes take effect January 1, when it is too late for most people to switch.

Once enrolled in a Part D plan, your opportunity to switch to a different plan is limited to the Open Enrollment Period from October 15 to December 7 every year. There are exceptions to this rule for people with special circumstances.

Individuals who are dually eligible (enrolled in both Medicare and Medicaid), enrolled in the Low Income Subsidy (“Extra Help”) or a Medicare Savings Program may change their enrollment in a Part D or Medicare Advantage Plan as often as once a month, with changes going into effect on the first day of the following month.

This overview is intended as a basic introduction to Medicare prescription drug plans, and is not intended to provide you with everything you need to make decisions about your prescription drug needs. Visit our resources page for information about who to call for more help with your Medicare Part D questions.

Medicare Rights Center

Medicare Rights Center (MRC) is the largest independent source of health care information and assistance in the United States for people with Medicare, and a collaborative partner of the National MS Society.

Learn More

Learn More

Centers for Medicare and Medicaid Services

Medicare is a government entitlement program administered by Centers for Medicare and Medicaid Services (CMS). Visit Medicare’s official website.

Learn More

Learn More


The National MS Society is Here to Help

Newly Diagnosed
If you or somone close to you has recently been diagnosed, access our MS information and resources.

Start Here

Start Here
© 2023 The National Multiple Sclerosis Society is a tax exempt 501(c)3 nonprofit organization. Its Identification Number (EIN) is 13-5661935.