Every year from October 15 through December 7, people already enrolled in Medicare can review, change, or renew their coverage for the upcoming year. The choices you make during this window will take effect on January 1, 2026.
This is the only time of year most beneficiaries can make changes unless they qualify for a Special Enrollment Period. It’s designed to ensure every person on Medicare has a fair chance to reassess their health needs and costs annually.
Purpose of the Medicare Open Enrollment Period
The annual enrollment period exists because Medicare Advantage (Part C) and Prescription Drug Plans (Part D) can change every year — including premiums, deductibles, covered drugs, pharmacy networks, and provider participation.
Open Enrollment gives you the opportunity to:
- Switch between Original Medicare and Medicare Advantage.
- Join, drop, or switch a Part D prescription drug plan.
- Change from one Medicare Advantage plan to another (with or without drug coverage).
Failing to review your plan can lead to unpleasant surprises — higher costs, discontinued coverage of certain medications, or losing access to your preferred doctors or hospitals.
Key Dates and What to Expect
By September 30, 2025 — Review Your Annual Notice of Change (ANOC)
Your insurance provider will mail your ANOC, detailing any changes to your plan that take effect January 1, 2026. Review this document carefully. If you haven’t received it by the end of September, contact your plan provider.
October 15 – December 7, 2025 — The Decision Window
During these seven weeks, you can compare plans, adjust your coverage, or stay with your current plan. Any change you make must be submitted by December 7.
January 1, 2026 — Your New Coverage Begins
The plan you selected will go into effect at the start of the new year.
Bonus for Medicare Advantage Enrollees:
From January 1 to March 31, 2026, people enrolled in Medicare Advantage can make a one-time switch to another Advantage plan or revert to Original Medicare. However, this window doesn’t allow switching Part D drug plans if you’re on Original Medicare.
Checklist: How to Avoid Missing the Window
- Read your ANOC carefully.
Look for any changes in premiums, copays, deductibles, and covered medications. - List your prescriptions.
Make sure your current drugs are still covered at an affordable cost and that your pharmacy remains in-network. - Check your healthcare providers.
Confirm that your primary doctor, specialists, and hospital are still part of your plan’s network. - Compare total annual costs.
Don’t just focus on the monthly premium—include the deductible, copays, and out-of-pocket expenses for the year. - Consider changes in your health.
If you’ve developed new conditions or need different specialists, make sure your plan suits your updated needs. - Use trusted resources for help.
Call 1-800-MEDICARE or contact your local State Health Insurance Assistance Program (SHIP) for free guidance. - Keep proof of continuous coverage.
If you go without creditable prescription coverage for more than 63 days, you may face a lifetime penalty when you re-enroll in a Part D plan. - Make your decision early.
Don’t wait until the last week of the enrollment period — plan comparison takes time, and call centers are busier near the deadline.
What Happens if You Miss the Window?
If you do nothing, your current plan will automatically renew with all its 2026 changes. That might sound convenient, but it could cost you more if your medications move to a higher tier, your provider leaves the network, or your premium increases.
Missing this enrollment window doesn’t typically trigger penalties — unless you’re enrolling in Medicare for the first time or you’ve gone too long without drug coverage. But it does mean you’ll have to wait until the next enrollment period to make adjustments, even if you discover your plan no longer meets your needs.
Common Mistakes to Avoid
- Ignoring your ANOC — it often hides cost or network changes that can surprise you later.
- Choosing based on premiums only — low premiums don’t always equal lower total costs.
- Assuming your prescriptions or doctors are still covered — verify every year.
- Waiting until the last minute — errors or missing information can delay your changes.
Who Should Pay Extra Attention in 2025?
- People taking multiple prescription drugs. Formularies change frequently.
- Those whose doctors or hospitals recently merged or changed networks.
- Beneficiaries on tight budgets. Inflation and plan adjustments can affect total out-of-pocket costs.
- New retirees who recently turned 65. Open Enrollment may be their first opportunity to make corrections to their coverage choices.
Medicare’s Annual Enrollment Period is more than an administrative task — it’s your annual opportunity to protect your health and your wallet. A little time spent comparing plans could mean hundreds of dollars saved in 2026 and better care coordination throughout the year.
Mark your calendar, review your mail, and don’t leave your coverage to chance.
-Phan Trần Hương-
References & Further Reading
- Medicare.gov — Open Enrollment Overview: https://www.medicare.gov/plan-compare
- Centers for Medicare & Medicaid Services (CMS) — Annual Notice of Change (ANOC): https://www.cms.gov
- Medicare.gov — Late Enrollment Penalties: https://www.medicare.gov/your-medicare-costs/part-b-costs/penalty
- Medicare.gov — Medigap Information: https://www.medicare.gov/supplements-other-insurance
- State Health Insurance Assistance Program (SHIP) — Free Local Help: https://www.shiphelp.org