What is Medicare Open Enrollment, and can I change plans later?
Open Enrollment happens from October 15 to December 7 and is the time each year when you can make changes to your coverage. The changes you make are effective January 1 of next year. In most cases, if you join a Medicare Advantage Plan, you must keep it for the calendar year. If you're already in one, you can make one change from January 1 to March 31.
What matters most
October 15 to December 7
Open Enrollment happens from October 15 to December 7 each year. The changes you make are effective January 1 of next year, and the plan must get your enrollment request by December 7.
What you can change
What you can do depends on the kind of coverage you have now. You can join, drop, or switch to another Medicare Advantage Plan, with or without drug coverage. If you're in Original Medicare, you can join, drop, or switch to another Medicare drug plan. You can also switch from Original Medicare to a Medicare Advantage Plan, or from a Medicare Advantage Plan to Original Medicare.
A second window for some
If you're already in a Medicare Advantage Plan, there's also a Medicare Advantage Open Enrollment Period, from January 1 to March 31 each year. You can only make one change during this period: switch to a different Medicare Advantage Plan, or switch to Original Medicare and join a separate Medicare drug plan.
Want the detail? How it works, a worked example and common mix-ups are in .
Words on this page
Open Enrollment
the time each year, October 15 to December 7, when you can make changes to your Medicare health or drug coverage for next year
Medicare Advantage Plan
a Medicare-approved plan from a private company that covers your Part A and Part B benefits, and usually drug coverage (also called Part C)
Special Enrollment Period
a chance to change coverage outside the usual periods when certain events happen in your life, like a move
Who can answer for your situation
You can compare plans at Medicare.gov/plan-compare or by calling 1-800-MEDICARE (1-800-633-4227). Your State Health Insurance Assistance Program (SHIP) gives free personalized health insurance counseling and isn't connected to any insurance company or health plan.
The one-time window to first sign up, which is different from yearly Open Enrollment.
What Open Enrollment is for
Review your Medicare health and drug coverage each year. Make sure it still meets your needs, and decide if you want to make a change. Open Enrollment, from October 15 to December 7, is the time each year when you can make changes to your coverage.
If you're in a Medicare Advantage Plan, review the "Annual Notice of Change" from your plan each year. It includes any changes in coverage, costs, and more that will be effective in January. Your plan will send you a printed or electronic copy by September 30.
What you can change
During Open Enrollment, what you can do depends on the kind of coverage you have now. You can join, drop, or switch to another Medicare Advantage Plan with or without drug coverage, or add or drop drug coverage. If you're in Original Medicare, you can join, drop, or switch to another Medicare drug plan. You can also switch from Original Medicare to a Medicare Advantage Plan, or from a Medicare Advantage Plan to Original Medicare.
If you switch to Original Medicare, you may need to join a separate drug plan and may want to add Medicare Supplement Insurance (Medigap). Medigap is extra insurance you can buy from a private health insurance company to help pay your share of out-of-pocket costs in Original Medicare. There are limits on when you can add it.
Changing plans after December 7
If you're already in a Medicare Advantage Plan, you can use the Medicare Advantage Open Enrollment Period, from January 1 to March 31 each year. You can switch to a different Medicare Advantage Plan, or switch to Original Medicare and join a separate Medicare drug plan. You can only make one change during this period, and any changes you make will be effective the first of the month after the plan gets your request.
During the January 1 to March 31 period, you can't switch from Original Medicare to a Medicare Advantage Plan. If you have Original Medicare, you also can't join a separate Medicare drug plan or switch from one Medicare drug plan to another.
In most cases, if you join a Medicare Advantage Plan, you must keep it for the calendar year starting the date your coverage begins. Generally, you must also stay in a Medicare drug plan for the entire year. But in certain situations, like if you move or you lose other insurance coverage, you may be able to join, switch, or drop a plan during a Special Enrollment Period.
An example
Say you're in Original Medicare with a Medicare drug plan, and in the fall you decide a different drug plan fits you better. During Open Enrollment, from October 15 to December 7, you can switch to another Medicare drug plan. The plan must get your enrollment request by December 7, and the change is effective January 1 of next year.
Common mix-ups
These are the pairs people most often mix up.
Open Enrollment vs. first sign-up
Open Enrollment is the time each year when you can make changes to your coverage. Generally, you first sign up for Part A and Part B in a different window, called your Initial Enrollment Period. It lasts for 7 months, starting 3 months before you turn 65 and ending 3 months after the month you turn 65.
Two different open enrollment periods
Open Enrollment happens from October 15 to December 7. The Medicare Advantage Open Enrollment Period, from January 1 to March 31, is only if you're already in a Medicare Advantage Plan. During it, you can't switch from Original Medicare to a Medicare Advantage Plan.
1 What the source says · Open Enrollment (introduction)
Open Enrollment happens from October 15 – December 7 and is the time each year when you can make changes to your coverage. The changes you make during Open Enrollment are effective January 1 of next year (the plan must get your enrollment request by December 7).
Checked October 1, 2026
2 What the source says · Your options during Open Enrollment
During Open Enrollment what you can do depends on the kind of coverage you have now.
Checked October 1, 2026
3 What the source says · Your options during Open Enrollment, Change your Medicare Advantage Plan
Join, drop, or switch to another Medicare Advantage Plan with or without drug coverage (or add or drop drug coverage).
Checked October 1, 2026
4 What the source says · Your options during Open Enrollment, Change your drug plan
Join, drop, or switch to another Medicare drug plan if you're in Original Medicare.
Checked October 1, 2026
5 What the source says · Your options during Open Enrollment, Change how you get coverage
Switch from Original Medicare to a Medicare Advantage Plan or from a Medicare Advantage Plan to Original Medicare.
Checked October 1, 2026
6 What the source says · What else should I know if I switch to Original Medicare?
If you switch to Original Medicare, you may need to join a separate drug plan and may want to add Medicare Supplement Insurance (Medigap). Medicare Supplement Insurance (Medigap) is extra insurance you can buy from a private health insurance company to help pay your share of out-of-pocket costs in Original Medicare. There are limits on when you can add it.
7 What the source says · Section 6: Medicare drug coverage (Part D), When can I join, switch, or drop a plan? (p. 84)
Medicare Advantage Open Enrollment Period (only if you're already in a Medicare Advantage Plan). From January 1 – March 31 each year, you can switch to a different Medicare Advantage Plan or switch to Original Medicare (and join a separate Medicare drug plan) once during this time (page 75).
Checked October 1, 2026
8 What the source says · Section 4: Medicare Advantage Plans & other options, Medicare Advantage Open Enrollment Period, January 1 to March 31 (p. 75)
You can only make one change during this period, and any changes you make will be effective the first of the month after the plan gets your request.
Checked October 1, 2026
9 What the source says · Section 4: Medicare Advantage Plans & other options, Medicare Advantage Open Enrollment Period, January 1 to March 31 (p. 75)
During this period, you can't: • Switch from Original Medicare to a Medicare Advantage Plan. • Join a separate Medicare drug plan if you have Original Medicare. • Switch from one Medicare drug plan to another if you have Original Medicare.
Checked October 1, 2026
10 What the source says · Get started with Medicare (p. 13)
Review your Medicare health and drug coverage each year. Make sure it still meets your needs, and decide if you want to make a change.
Checked October 1, 2026
11 What the source says · Section 4: Medicare Advantage Plans & other options, Read the information you get from your plan (p. 67)
If you're in a Medicare Advantage Plan, review the "Annual Notice of Change" and "Evidence of Coverage" from your plan each year. • Annual Notice of Change: Includes any changes in coverage, costs, and more that will be effective in January. Your plan will send you a printed or electronic copy by September 30.
Checked October 1, 2026
12 What the source says · Section 4: Medicare Advantage Plans & other options, Special Enrollment Period (p. 76)
In most cases, if you join a Medicare Advantage Plan, you must keep it for the calendar year starting the date your coverage begins. However, in certain situations, like if you move or you lose other insurance coverage, you may be able to join, switch, or drop a Medicare Advantage Plan during a Special Enrollment Period (page 84).
Checked October 1, 2026
14 What the source says · Section 6: Medicare drug coverage (Part D), Special Enrollment Periods (p. 84)
Generally, you must stay in your plan for the entire year. But when certain events happen in your life, like if you move or lose other insurance coverage, you may be able to qualify for a Special Enrollment Period to join, switch, or drop a Medicare drug plan or a Medicare Advantage Plan with drug coverage.
13 What the source says · Your first chance to sign up (Initial Enrollment Period)
This is called your Initial Enrollment Period. It lasts for 7 months, starting 3 months before you turn 65, and ending 3 months after the month you turn 65.
15 What the source says · Your answer: Sign up when you're first eligible
Generally, you're first eligible to sign up for Part A and Part B starting 3 months before you turn 65 and ending 3 months after the month you turn 65.
Checked October 1, 2026
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If something here doesn’t match what you’ve been told, please check with 1-800-MEDICARE, and let us know through our Contact page.
General education, not individualized advice. For your own situation, you can call 1-800-MEDICARE or your State Health Insurance Assistance Program (SHIP).
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