Once you've signed up for Original Medicare (Parts A and B), you can enroll in Medicare Advantage during your Initial Enrollment Period. This starts three months before your 65th birthday month and ends three months after it.
You may qualify for a Special Enrollment Period if you experience certain life events, such as moving out of your current plan’s service area or losing your employer-based health coverage.
You can also add, switch, or drop your plan during the Medicare Annual Enrollment Period, from October 15 through December 7 each year.
And the Medicare Advantage Open Enrollment Period – January 1 to March 31 – offers a one-time opportunity to change your plan.