The short answer
When can I enroll in or change Medicare coverage?
Medicare enrollment timing depends on your eligibility, current coverage, and the change you want to make. Common windows include the Initial Enrollment Period around first eligibility, Annual Enrollment from October 15 through December 7, Medicare Advantage Open Enrollment from January 1 through March 31, and event-specific Special Enrollment Periods.
Use this guide to understand the basics, then verify current coverage rules and costs before you enroll.
Initial Enrollment Period
For many people, the Initial Enrollment Period is a seven-month window that begins three months before the month they turn 65, includes their birthday month, and ends three months afterward. Different timing can apply if Medicare eligibility is based on disability or another circumstance.
Annual Enrollment Period
From October 15 through December 7, people with Medicare can generally review and change Medicare Advantage or Part D coverage for the next calendar year. This is a useful time to recheck medications, providers, benefits, and costs.
Medicare Advantage Open Enrollment Period
From January 1 through March 31, people already enrolled in Medicare Advantage can generally switch to another Medicare Advantage plan or return to Original Medicare and join a standalone Part D plan. This period does not allow every type of change.
Special Enrollment Periods
Certain events may create a Special Enrollment Period, such as losing qualifying employer coverage, moving outside a plan's service area, or qualifying for certain assistance programs. The allowed change and deadline depend on the event.
- Do not assume a life event automatically qualifies.
- Keep notices that show when coverage ended or your circumstances changed.
- Confirm exact timing with Medicare.gov, Social Security, or a licensed insurance agent.
Illustrative example
A birthday-month timeline
For a person whose Medicare eligibility begins around an August 65th birthday, the standard seven-month Initial Enrollment Period generally runs from May through November. Coverage start timing can depend on when enrollment occurs, and different rules can apply because of disability, employer coverage, or another circumstance.
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Related questions
Frequently asked questions
What is the Medicare Initial Enrollment Period?
For many people, it is a seven-month period beginning three months before the month they turn 65, including their birthday month, and ending three months afterward.
When is Medicare Annual Enrollment?
Annual Enrollment generally runs from October 15 through December 7. People with Medicare can review and make certain Medicare Advantage or Part D changes for the next calendar year.
Can I change Medicare Advantage plans from January through March?
People already enrolled in Medicare Advantage can generally make one allowed change during Medicare Advantage Open Enrollment, but the period does not permit every type of change.
What happens if I miss Medicare enrollment?
You may face a coverage gap or late-enrollment penalty unless another enrollment opportunity or qualifying coverage applies. Confirm your situation with Medicare or Social Security.
Does moving create a Special Enrollment Period?
A move can create a Special Enrollment Period in certain situations, such as leaving a plan's service area. The permitted change and deadline depend on the circumstances.
Primary sources
- Get started with Medicare — Medicare.gov
- Sign up for Medicare — Social Security Administration
- Your Medicare coverage choices — Medicare.gov