The short answer
Medicare Open Enrollment runs October 15 to December 7. It is the window for joining, dropping or switching a Medicare Advantage plan or a Medicare drug plan. A change made in it starts January 1 of the next year, and the plan must have your enrollment request by December 7.
Plan year 2026. The dates above are fixed by the enrollment period table on Medicare.gov, read on August 7, 2026. They are statutory dates rather than figures that change with the plan year, so no year is attached to them inside the sentence.
Say you decide in October. Your coverage still begins on January 1, the same as somebody who decided on December 6. Inside this window the date you act does not move the date you are covered.
When is Medicare Open Enrollment?
Medicare Open Enrollment runs October 15 to December 7 each year. It is the window for joining, dropping or switching a Medicare Advantage plan or a Medicare drug plan. A change made in it starts January 1 of the next year, and the plan must have your request by December 7.
It exists because Medicare plan changes are not open all year. You can only join, switch or drop a Medicare Advantage plan, another Medicare health plan, or a Medicare drug plan at certain times, called enrollment periods, and this is the one that comes round for everybody.
Two other windows sit near it and are often confused with it. The Medicare Advantage Open Enrollment Period runs January 1 to March 31 and is only for people already in a Medicare Advantage plan. Special Enrollment Periods are triggered by life events rather than dates. Each runs on a different trigger, a date for one and an event for the other.
What can I change during Open Enrollment?
Medicare Open Enrollment allows four kinds of change. Join, drop or switch a Medicare Advantage plan, with or without drug coverage. Move between Original Medicare and a Medicare Advantage plan, in either direction. Add or drop drug coverage. Join, drop or switch a Medicare drug plan if you are in Original Medicare.
Notice what that list covers. Reading the enrollment table's rows side by side, this is the only window on it where the move between Original Medicare and Medicare Advantage runs in both directions for everybody. The rows are the government's; the reading across them is ours.
This is the widest window in the Medicare year, and the list of what it allows is long.
| What you want to do | Allowed here | Starts |
|---|---|---|
| Join, drop or switch a Medicare Advantage plan | Yes | January 1 |
| Switch between Original Medicare and Advantage | Yes, both directions | January 1 |
| Join, drop or switch a drug plan | Yes | January 1 |
Every row starts on the same date, which is the thing to hold. Nothing you do in this window takes effect before the new year.
The drug plan rule carries a condition worth reading twice. Joining, dropping or switching a separate Medicare drug plan during this window is described for people in Original Medicare. Most Medicare Advantage plans include drug coverage in the plan itself.
There are joining requirements underneath all of it. You generally need Part A and Part B, or one of them for a drug plan. You must live in the plan's service area. You must meet a citizenship or lawful presence requirement. And you need your Medicare Number and your coverage start dates, both of which are on your Medicare card.
Those requirements are not window rules. They apply whenever you join, in any enrollment period, which is why they are worth checking before October rather than during it.
When do my changes take effect?
A change made during Medicare Open Enrollment takes effect January 1 of the next year, and the plan must get your request by December 7. Call it the Deadline Is Not The Date: the paperwork closes on December 7 and the coverage changes on January 1.
The Deadline Is Not The Date is our naming for what one published sentence does. Medicare.gov puts both dates in the same line of its enrollment table. The dates are the government's. Naming the gap between them is ours.
That gap has a practical meaning. Between December 7 and January 1 you are still in your old plan, under its old rules and its old costs, even though the decision is already made and cannot be changed through this window.
The word must in that sentence is doing real work too. The deadline is when the plan has your request, not when you posted it. A paper form has to arrive before the period ends.
What happens if I miss December 7?
Missing December 7 closes this route until the following October 15, but it does not close every route. Two others exist. The Medicare Advantage Open Enrollment Period, January 1 to March 31, is open to anyone already in a Medicare Advantage plan. A Special Enrollment Period may open if a qualifying life event happens.
Those two are not substitutes for each other. The January window is defined by what you already hold. A Special Enrollment Period is defined by something happening to you, such as moving or losing other coverage.
If neither applies, the next general opportunity is the following Open Enrollment Period. For Medicare Cost Plans, demonstration or pilot programs, and the Program of All-inclusive Care for the Elderly, the instruction is different again: contact those plans directly about when you can join.
Do I need to do anything to stay in my plan?
Medicare.gov does not require any action to stay in a plan you already have. Open Enrollment is described as the period when you can join, drop or switch, and none of those verbs applies to staying put. The window is an opportunity rather than a renewal.
What changes without you is a separate question, and it is the reason the window matters even to someone content with their plan. Insurance companies decide each year whether to join or leave Medicare, and they decide whether a plan is offered across a whole state or only in certain counties.
Medicare.gov's enrollment table does not describe the notices a plan sends about its own changes, so this article does not describe them either. What the table does say is that Open Enrollment is the general chance to act if you want to.
There is one thing worth confirming rather than assuming, and it is a joining requirement rather than a renewal. A plan requires you to live in its service area, so a move during the year is the kind of change that can matter even to someone otherwise content.
How do I actually join or switch a plan?
Three routes are named for joining or switching. Select Enroll for the plan you want at Medicare.gov/plan-compare. Contact the plan directly by phone, on its website, or by asking for a paper form. Or call 1-800-MEDICARE at 1-800-633-4227, TTY 1-877-486-2048.
The paper form carries the one condition that catches people. The plan must get it before your enrollment period ends, so the postmark is not the deadline and the arrival is.
Before joining, four routes are named for finding and comparing plans. Two are documents: the comparison tool on Medicare.gov, and the plan list in the back of the Medicare and You handbook. Two are people: a trusted agent or broker, and free personalized counseling from your State Health Insurance Assistance Program.
That last one carries its own qualifier on the page, and the qualifier is the reason it is listed. These programs are not connected to any insurance company or health plan.
What this means for you
Open Enrollment is the one window in the year that is open to everyone with Medicare, and it runs October 15 to December 7. On the enrollment table it is the only row carrying the move between Original Medicare and Medicare Advantage in both directions for anybody who wants it.
Two dates, not one. December 7 is when the plan must have your request. January 1 is when your coverage actually changes. Nothing about your care changes in between.
Doing nothing is a valid choice and needs no paperwork. The window exists so you can act, not so you can renew. Nothing on Medicare.gov's enrollment table asks you to confirm a plan you already hold.
For the January window that follows it, read the Medicare Advantage Open Enrollment article in this cluster. For the life events that open a window of their own, read the Special Enrollment Period article beside it.
FAQ
Is the deadline the day I decide or the day the plan gets my request?
The day the plan gets your request. Medicare.gov states it inside the coverage line for this window: your change starts January 1 of the next year, and the plan must get your enrollment request by December 7. That wording matters most for anyone using a paper form.
You can ask a plan for a form to fill out and mail back, but the plan has to receive it before your enrollment period ends, so posting it on December 6 is not the same as meeting the deadline.
The two faster routes avoid the question entirely: selecting Enroll for a plan at Medicare.gov/plan-compare, or calling the plan or 1-800-MEDICARE directly, both put the request in the plan's hands the same day.
Can I switch from Medicare Advantage back to Original Medicare in this window?
Yes. Medicare.gov lists that move explicitly among the changes this period allows: you can switch from Original Medicare to a Medicare Advantage plan, or from a Medicare Advantage plan to Original Medicare. It is worth knowing that this is not the only chance to make that particular move.
The Medicare Advantage Open Enrollment Period, January 1 to March 31, also lets someone drop a Medicare Advantage plan and return to Original Medicare, and adds that they will also be able to join a separate Medicare drug plan.
How the two windows differ in who may use them is the subject of the Medicare Advantage open enrollment article in this cluster.
What is the difference between joining a plan and changing my Medicare itself?
They are two different things, and this article is about the second one. Joining, dropping or switching a Medicare Advantage plan or a Medicare drug plan happens in the enrollment periods described here. Getting Medicare Part A and Part B in the first place is a separate subject with its own article in the Enrollment menu.
The two connect through a requirement rather than a schedule: to join a Medicare Advantage plan you need both Part A and Part B, and to join a Medicare drug plan you need either Part A or Part B.
Someone new to Medicare also has an Initial Enrollment Period for plan choices, which starts 3 months before they get Medicare and ends 3 months after.
I just joined a Medicare Advantage plan. Am I stuck with it until October?
No. Medicare.gov names a separate opportunity for exactly that situation. If you joined a Medicare Advantage plan during your Initial Enrollment Period, you can change to another Medicare Advantage plan, with or without drug coverage, or go back to Original Medicare with or without a drug plan, within the first 3 months you have Part A and Part B.
Separately, the Medicare Advantage Open Enrollment Period runs January 1 to March 31 for anyone already in a Medicare Advantage plan. Both are covered in the companion article in this cluster. The general rule holds underneath them: plan changes happen in defined windows, not on demand.
Who can help me compare plans without selling me one?
Your State Health Insurance Assistance Program. Medicare.gov lists it among four routes for finding and comparing plans, alongside the comparison tool on Medicare.gov, the plan list in the back of the Medicare and You handbook, and a trusted agent or broker.
The reason it carries its own qualifier is the qualifier itself: Medicare.gov states that these programs are not connected to any insurance company or health plan, and that the counseling is free and personalized.
For anyone weighing a switch during a window that closes on a fixed date, the independence matters, because the answer may be that staying put is the option that needs no paperwork at all.
