Medicare Enrollment Periods: The Quick Reference

The fixed windows when you can sign up for Medicare or change your Medicare coverage.

Key takeaways

• Initial Enrollment Period: 7 months: the 3 months before the month you turn 65, that month, and the 3 months after
• Open Enrollment: October 15 to December 7 each year, for changes that start January 1
• Most useful single change: Mark your Initial Enrollment Period on a calendar several months before you turn 65.
• Commonest mistake: Assuming COBRA or retiree coverage lets you delay Part B without a penalty.
• See a doctor if any of the signs under "When to speak to a doctor" below apply to you.

The numbers, in one place

In one paragraph

Missing your first chance to enroll can mean gaps in coverage and late penalties that last as long as you have Medicare.

Worth doing

• Mark your Initial Enrollment Period on a calendar several months before you turn 65
• If you are still working, ask your employer how your coverage works with Medicare
• Review your coverage every fall during Open Enrollment
• Get free help from your State Health Insurance Assistance Program (SHIP)

Worth avoiding

• Assuming COBRA or retiree coverage lets you delay Part B without a penalty
• Waiting for a reminder that may never come if you are not yet getting Social Security
• Making plan changes outside the allowed periods and expecting them to take effect

Related topics

• What the Guidance Really Says About Open and Special Enrollment (Health Insurance and Costs)
• Returning to Work After Illness: What Published Guidance Supports (Workplace Health)
• Annual Wellness Visit: What the Evidence Actually Says (Preventive Care)
• The Evidence on Assistive Equipment, Without the Hype (Rehabilitation)

Where to go next

• Medicare Enrollment Periods: A Practical Checklist
• Myths About Medicare Enrollment Periods, Checked Against the Guidance
• Medicare Enrollment Periods — the reference entry
• Medicare and Medicaid: The Complete Guide
• The Evidence on Medigap Policies, Without the Hype
• Medicaid Eligibility: Sorting the Evidence From the Noise

When to speak to a doctor

If you are close to 65 and unsure whether you need to sign up, call Social Security or 1-800-MEDICARE (1-800-633-4227) before your Initial Enrollment Period ends. A coverage question should never delay emergency care; call 911 in an emergency.

Where this comes from

• Medicare.gov — When does Medicare coverage start?
• Medicare.gov — Joining a plan

How this page was put together

Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.

Medical disclaimer

This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.