What Medicare Open Enrollment actually lets you change

Medicare Open Enrollment is the Annual Election Period that runs from October 15 through December 7. In that window you can join, drop, or switch a Medicare Advantage plan, and you can join, drop, or switch a Part D drug plan. Changes filed in that window take effect on January 1.

What the window covers

The Annual Election Period is a Medicare plan-choice window. It is the time of year when most people already on Medicare can move between Original Medicare and Advantage, change Advantage contracts, or change how they get Part D.

It does not enroll you in Part A or Part B for the first time. Those parts use their own initial and general enrollment rules. A confirmation that names an Advantage or Part D plan for January 1 is not a new Medicare card for Parts A and B.

What it is not

A Medigap Open Enrollment Period is a different clock. That six-month window usually starts when you are 65 or older and enrolled in Part B. It is about buying a Supplement that sits on Original Medicare. The October–December Annual Election Period does not reopen Medigap guaranteed-issue rights on its own.

Marketplace open enrollment is another calendar. It is the yearly window for individual health plans sold on or off the Health Insurance Marketplace. Selecting a Marketplace plan does not file an Advantage or Part D election. Filing a Medicare Advantage change does not enroll you in a Marketplace plan.

The usual mix-up

People treat every fall letter as if it opened every kind of coverage. A Medicare Annual Notice of Change is about next year’s Advantage or Part D contract. A Marketplace notice is about an individual plan year. A Medigap mailing is about a Supplement. The envelope season can overlap. The windows do not.

January 1 through March 31 is a narrower Medicare Advantage Open Enrollment Period for people already in an Advantage plan. That later window is not the October 15–December 7 Annual Election Period, and it is not a Medigap season.

What to read on the document

On the notice, read the plan name, the year it applies to, and the effective date. If the date is January 1, confirm whether the contract is Advantage, Part D, a Supplement, or a Marketplace plan. Then read the enrollment period named on that same page. A fall postmark does not move a Medigap clock or a Marketplace clock.

Educational only · Not medical, insurance, or legal advice