📋 Facts sourced from Medicare & You 2026, the official U.S. government Medicare handbook.

The Four Enrollment Periods for Medicare Advantage

🟣 Initial Enrollment Period — Around your 65th birthday
Your First Chance to Join

During the same 7-month window you use to enroll in Part A and Part B (3 months before your birthday month through 3 months after), you can also join a Medicare Advantage Plan. This is your most protected enrollment window — and the time when your Medigap rights are strongest. If you're turning 65, this is when to make the Original Medicare vs. Medicare Advantage decision with the full picture in view.

🔵 October 15 – December 7 each year — Open Enrollment Period (OEP)
Annual Open Enrollment — The Main Switch Window

According to Medicare & You 2026, this is the primary annual window for making Medicare health and drug coverage changes. During Open Enrollment, you can join a Medicare Advantage Plan for the first time, switch from one Medicare Advantage Plan to another, switch from Medicare Advantage back to Original Medicare (and join a Part D plan), or join, switch, or drop a Medicare drug plan. Coverage changes made during Open Enrollment take effect January 1 of the following year. New coverage begins January 1, 2027 for changes made during October 15 – December 7, 2026.

🟢 January 1 – March 31 each year — Medicare Advantage Open Enrollment Period (MA OEP)
A Second Chance — But Limited

According to Medicare & You 2026, if you're already enrolled in a Medicare Advantage Plan, you can use this period to switch to a different Medicare Advantage Plan or switch back to Original Medicare (and join a separate drug plan). Changes take effect the first day of the month after the plan receives your request. Important: During the MA OEP, you cannot switch from Original Medicare to a Medicare Advantage Plan, join a Medicare drug plan if you're in Original Medicare, or switch between drug plans if you're in Original Medicare.

🟡 Special Enrollment Periods — When qualifying life events occur
Mid-Year Changes for Qualifying Circumstances

According to Medicare & You 2026, there are specific circumstances that allow you to join, switch, or drop a Medicare Advantage Plan outside of the standard enrollment windows. Common qualifying events include:

  • You move out of your plan's service area
  • You move to a new address and new plans are available
  • Your plan is leaving Medicare or stopping coverage in your area
  • You qualify for Extra Help (Low Income Subsidy) for drug costs
  • You qualify for or lose Medicaid
  • You move into or out of a nursing home or other care facility
  • You were enrolled in a plan that was not properly marketed to you
  • You're a new enrollee in Medicare (within your first year in a plan)

Your First Year in Medicare Advantage: Trial Rights

If you're new to Medicare and join a Medicare Advantage Plan, you have a special trial right during your first 12 months. If you decide Medicare Advantage isn't right for you within that window, you can switch back to Original Medicare and — critically — you have a guaranteed right to buy any Medigap plan available in your state during that transition, without medical underwriting.

This trial right exists because Medicare recognizes that many people don't fully understand what they're signing up for until they've actually tried it. After your first year, this trial right no longer applies.

Leaving Medicare Advantage after your first year: Medigap risk

If you leave Medicare Advantage after your 12-month trial period ends and want to enroll in a Medigap plan, insurers in most states can use medical underwriting — meaning they can deny you coverage or charge you substantially higher rates based on your health. This is one of the most significant and underappreciated risks of enrolling in Medicare Advantage at 65. If you decide to switch back at 75 after a serious illness, Medigap may no longer be accessible at any reasonable price.

Review Your Plan Every Year

Medicare Advantage Plans can change their premiums, cost-sharing, benefits, formularies, and provider networks annually. According to Medicare & You 2026, by October 1 you should start comparing your current coverage with options for the coming year. Your plan will send an Annual Notice of Change (ANOC) before October 15 showing what's changing. Don't ignore it — a plan that worked well in 2026 may have cut your doctors, changed your drug formulary, or raised copays significantly for 2027.

Key 2026 enrollment dates

January 1–March 31, 2026: Medicare Advantage Open Enrollment Period (existing MA enrollees only). October 1, 2026: Begin comparing plans for 2027. October 15–December 7, 2026: Open Enrollment — make changes effective January 1, 2027. January 1, 2027: New coverage begins.

How to Actually Enroll

To join a Medicare Advantage Plan, you can contact the plan directly, use Medicare.gov/plan-compare to compare and enroll, call 1-800-MEDICARE (1-800-633-4227), or work with a licensed Medicare broker like Betsy. You must have Part A and Part B, live in the plan's service area, and not have End-Stage Renal Disease in most cases (though ESRD restrictions have been relaxed for many plans starting in 2021).

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Betsy's Take

"The October 15 through December 7 window is when I'm busiest — and for good reason. It's when people can actually change their coverage for the coming year. But the conversation shouldn't start on October 15. It should start in September, when you have time to look at the Annual Notice of Change, check whether your doctors are still in-network, verify your prescriptions are still on the formulary, and compare what else is available. Call me in September."

Talk to Betsy — Free Consultation