When Can You Change Your Medicare Plan? Enrollment Periods Explained

Fall Open Enrollment: October 15 - December 7

This is the big window most people think of as "Medicare open enrollment." It runs the same dates every year, October 15 through December 7. Your plan must receive your request by December 7, and any change you make takes effect January 1 of the following year.

This period gives you the most freedom of any window in the Medicare year. You can switch in almost any direction, and you can make as many changes as you want during the window. Only the last change you make by December 7 counts.

• Join, drop, or switch a Medicare Advantage plan (with or without drug coverage)
• Switch from Original Medicare to a Medicare Advantage plan, or from a Medicare Advantage plan back to Original Medicare
• Join, drop, or switch a standalone Part D prescription drug plan
• Add or drop drug coverage
• All changes take effect January 1

Medicare Advantage Open Enrollment Period: January 1 - March 31

There is a second, smaller window from January 1 through March 31, but it is open only to people who are already enrolled in a Medicare Advantage plan on January 1. If you are in Original Medicare, this period does not apply to you.

You can make just one change during this window, and it takes effect on the first day of the month after your plan receives the request. For example, a change processed in February would start March 1.

• Switch to a different Medicare Advantage plan, OR
• Drop your Medicare Advantage plan and return to Original Medicare (and add a standalone Part D drug plan if you want)
• You cannot use it to switch FROM Original Medicare TO a Medicare Advantage plan
• If you are in Original Medicare, you cannot use it to join a standalone Part D plan
• Only one change is allowed

When You First Join at 65: Initial Enrollment and the Trial Right

When you first become eligible for Medicare, you get a 7-month Initial Enrollment Period to join a Medicare Advantage or Part D drug plan. It includes the 3 months before the month you turn 65, the month you turn 65, and the 3 months after.

There is also a special safety net for first-timers. If you join a Medicare Advantage plan when you first enroll and decide it is not right for you, you have a one-time trial right to drop it at any time during the next 12 months and return to Original Medicare.

Waiting too long to get drug coverage can cost you. If you go 63 or more days in a row without Medicare drug coverage or other creditable drug coverage after your Initial Enrollment Period ends, you may owe a Part D late enrollment penalty. The penalty is 1% of the national base beneficiary premium ($38.99 per month in 2026) times the number of full months you went without coverage, rounded to the nearest $0.10, and it is added to your premium for as long as you have Part D.

Special Enrollment Periods: Changing Plans After a Life Event

Special Enrollment Periods (SEPs) let you change your Medicare Advantage or drug coverage outside the normal windows when certain life events happen. Each SEP has its own rules and time limits.

• Moving: You move out of your plan's service area, or move to an area that offers new plan options.
• Losing other coverage: You lose other creditable coverage, or leave employer or union coverage (including COBRA). In general, this SEP lasts for 2 full months after the month your coverage ends.
• 5-star plans: The 5-star Special Enrollment Period lets you switch once to a 5-star-rated Medicare Advantage plan, Medicare Cost Plan, or Part D drug plan available in your area. It can be used only once between December 8 of the prior year and November 30 of the plan year.
• Extra Help or Medicaid: If you get Extra Help (the Part D Low-Income Subsidy) or have Medicaid, you can change your Medicare drug coverage once per calendar month, with the change taking effect the first day of the next month.

Medigap (Medicare Supplement) Works Differently

Medigap policies are not part of the annual open enrollment windows above. There is no yearly open enrollment for Medigap.

Instead, you get a one-time, 6-month Medigap Open Enrollment Period that starts the first month you are both 65 or older AND enrolled in Part B. During this window, insurers cannot deny you a policy or charge you more because of your health.

After that 6-month window closes, there is in most cases no federal right to switch or buy a Medigap policy. The exception is if you have a guaranteed issue right (also called a Medigap protection) from a qualifying situation. Without one, insurers can use medical underwriting, meaning they can review your health and charge more or turn you down. Some states offer broader Medigap rights, so check the rules where you live.

How to Actually Make a Change

Once you are in a valid enrollment window, making a change is straightforward. You do not have to cancel your old Medicare Advantage or Part D plan separately, joining a new one automatically disenrolls you from the old one.

• Use the Plan Finder at Medicare.gov to compare plans in your ZIP code and enroll online
• Call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048, available 24/7
• Contact the plan directly to enroll
• Get free, unbiased help from your State Health Insurance Assistance Program (SHIP)
• Keep a record of your confirmation number and the date your plan received the request