When can I switch my Medicare plan? - Medicare and You Handbook - A Guide to Medicare

When can I switch my Medicare plan?
Generally, if you join a Medicare Advantage Plan or Medicare Prescription Drug Plan, you can only change plans from October 15 through December 7 of every year.

This change will be effective January 1 of the following year.

For more information, see:

Who can join a Medicare Prescription Drug Plan?
When can I join a Medicare Advantage Plan or Medicare Prescription Drug Plan available in my area?
How do I join a Medicare Advantage Plan or Medicare Prescription Drug Plan?

If you are also eligible for Medicaid, you can switch plans at anytime.

(Primary Source: Centers for Medicare and Medicaid Services - Medicare and You Handbook. This content may have been enhanced by this site to include further examples, explanations, and links.)