When can I join a Part D prescription drug plan — or switch plans if I already have coverage?

​Because Medicare covers many of your health care expenses except for prescription drug coverage, when it comes to signing up for Part D or changing your current drug plan, timing is everything.

You have two ways to get coverage: Buy a stand-alone Part D prescription drug plan, or sign up for a Medicare Advantage plan that combines medical and drug coverage. Private insurance companies that Medicare regulates offer both types of plans. Keep in mind, you can enroll only during certain times:

• Initial enrollment period, the seven-month period that begins on the first day of the month that falls three months before the month you turn 65 and lasts for three months after the birthday month.

• Open enrollment period, which runs annually from Oct. 15 to Dec. 7, with coverage beginning Jan. 1. You also can switch to a different Part D or Medicare Advantage plan during this time.​

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Who can change Part D plans during special enrollment?

You may be able to sign up or switch Part D plans at other times if you’re eligible for a special enrollment period. To qualify, you need to meet certain criteria, such as if you:

• Lose health care coverage from your employer or union. You usually have up to two months to join a Part D or Medicare Advantage plan.

• Lose drug coverage that is considered to be at least as good as a basic Part D plan, called “creditable coverage.” Then you usually have up to two months to get Part D or a Medicare Advantage plan with drug coverage. Creditable coverage may come from an employer, a retiree plan, Tricare or another source. You’ll usually receive a notice every September letting you know if your coverage is creditable.

• Move to a new address that isn’t in your plan’s service area. You usually have up to two months to switch to a new Part D or Medicare Advantage plan.

• Receive financial assistance from the Part D Extra Help program. You can switch Part D plans as much as once per calendar quarter during the first three quarters of the year.

• Find a Medicare Advantage or Part D plan in your area that received a five-star quality rating from the Centers for Medicare & Medicaid Services (CMS). You can join that plan during the five-star special enrollment period, which lasts from Dec. 8 through Nov. 30 of the following year. It can be used once a year. Enrollment takes effect the first day of the month after the plan receives the enrollment request.

For more information about special enrollment periods, visit Medicare.gov.