Medicare Open Enrollment Period: Dates, Rules & What You Can Change (2026)

What Is Medicare Open Enrollment?

Medicare Open Enrollment \u2014 officially called the Annual Enrollment Period (AEP) \u2014 is the yearly window for people with Medicare to review and change their health or drug coverage for the following year. If you're newly eligible for Medicare, your Initial Enrollment Period is generally your first chance to enroll.

Outside of this period (and a few other special enrollment windows), your Medicare coverage is generally locked in for the year. That's why it's important to review your options each fall and make sure your current plan still meets your needs.

Note: Medicare Open Enrollment is different from the Initial Enrollment Period (when you first become eligible for Medicare at 65) and the Medigap Open Enrollment Period (for purchasing supplemental insurance).

2026–2027 Medicare Enrollment Dates & Deadlines

• Annual Enrollment Period (AEP)

  October 15 – December 7, 2026

  The main enrollment window. Changes take effect January 1, 2027.

• Medicare Advantage Open Enrollment (MA OEP)

  January 1 – March 31, 2027

  Only for people already in a Medicare Advantage plan. Switch MA plans or return to Original Medicare and, if needed, join a Part D plan.

• General Enrollment Period (GEP)

  January 1 – March 31, 2027

  For people who missed their Initial Enrollment Period. Sign up for Part B and, if you must buy it, Part A. Coverage starts the month after you sign up.

What You Can Do During Open Enrollment

Medigap follows separate enrollment rules. You may apply for a policy outside AEP, but an insurer may use medical underwriting unless you qualify for protected enrollment rights.

All Medicare Enrollment Periods Explained

Medicare has multiple enrollment windows. Here's how they differ:

For detailed information about each period, visit our Annual Enrollment Period guide or Turning 65 enrollment guide.

Tips for Medicare Open Enrollment

1. 1

   Review Your Annual Notice of Change (ANOC)

   Your plan must provide this by September 30, either on paper or electronically. It explains changes to costs and coverage for the coming year. If you do not receive it, contact your plan.

2. 2

   Check Your Medications

   Make sure your prescriptions are still on your plan’s formulary. Drug tiers and costs can change annually.

3. 3

   Verify Your Doctors Are Still In-Network

   Provider networks change every year. Confirm your doctors, specialists, and preferred hospitals are still covered.

4. 4

   Compare Total Costs, Not Just Premiums

   A $0 <strong>premium</strong> plan may cost more overall if it has high copays for services you use frequently.

5. 5

   Don’t Wait Until December 7

   Start reviewing options in October. Last-minute decisions often lead to mistakes or missed deadlines.

Common Open Enrollment Mistakes to Avoid

• Assuming your plan stays the same

  Plans change benefits, costs, and networks annually. Always review your ANOC.

• Only comparing premiums

  Factor in deductibles, copays, drug costs, and out-of-pocket maximums for a true cost picture.

• Relying only on the Star Rating

  CMS Star Ratings summarize quality and performance across multiple measures, but do not guarantee your individual experience. Compare benefits, costs, networks, and drug coverage too.

• Overlooking total prescription costs

  The Part D coverage gap ended in 2025. Compare each plan's formulary, drug tiers, deductible, pharmacy network, and estimated annual costs for your medications.

For covered Part D drugs, the annual out-of-pocket threshold is $2,100 in 2026 and $2,400 in 2027. After you reach it, you pay nothing out of pocket for covered Part D drugs for the rest of that calendar year. See Medicare's Part D cost guide.

Frequently Asked Questions

What happens if I miss Medicare Open Enrollment?

Can I change my Medigap plan during Open Enrollment?

Do I have to do anything during Open Enrollment if I’m happy with my plan?

When do changes made during Open Enrollment take effect?

Can I switch from Medicare Advantage to Original Medicare during Open Enrollment?