Medicare Open Enrollment 2026: What You Can Change by Dec. 7

Medicare open enrollment runs October 15 through December 7 every year, and a Medicare health or drug plan change you make in that window starts January 1. So if the plan mail on your kitchen table (or your dad's) has you wondering whether you need to do anything, the honest answer is that what you can change depends on what you have now.1

In This Guide

• What You Can Change During Medicare Open Enrollment
• The Fall Calendar, Date by Date
• Before You Decide: Read Your Plan's Annual Notice of Change
• What Happens If You Do Nothing
• Leaving Medicare Advantage for Original Medicare
• Missed Medicare Open Enrollment or Changed Your Mind?
• Outside These Windows: Special Enrollment Periods
• How to Review and Switch, Step by Step
• Frequently Asked Questions
• Learn More

What You Can Change During Medicare Open Enrollment

Medicare Open Enrollment is the fall window that Section 1851 of the Social Security Act calls the "annual, coordinated election period," and the law sets it at October 15 through December 7 for every year since 2012. You'll also hear it called the Medicare annual enrollment period, or AEP.1

So what can you actually do? Medicare's own fall guide, Your Yearly Medicare Review, puts it in one line: "During Open Enrollment, you can join, switch, or drop a Medicare Advantage Plan or Medicare drug plan, switch to Original Medicare, or keep your current coverage." The trick is that the options sort by what you have right now.1

That's the full menu from Medicare's enrollment-periods fact sheet: four kinds of moves, and "keep what you have" is one of them.1

Take a dad in Original Medicare who wants a different drug plan. Medicare Open Enrollment lets him join, drop, or switch Medicare drug plans because he's in Original Medicare, and the new drug plan starts January 1, as long as that plan gets his enrollment form by December 7.1

The Fall Calendar, Date by Date

The dates matter more than people think, and one of them is about when the plan receives your form, not when you send it.

Don't treat December 7 as a mailing date. If you're filling out a paper form on December 6, the plan may not have it in hand by December 7, and Medicare's rule is about the plan getting it.

Before You Decide: Read Your Plan's Annual Notice of Change

Your plan's Annual Notice of Change is the letter that tells you what's different next year. In its fall 2026 guide, Medicare tells people to "review any information you get from your current plan, including the 'Annual Notice of Change' letter, to learn how costs and benefits may change in 2027."3

If you're in a Medicare Advantage Plan, there's a legal floor behind that letter. Under 42 CFR 422.111, Medicare Advantage plans must notify members of January 1 changes at least 15 days before October 15, which means by September 30. That rule is a notification deadline for Medicare Advantage organizations, so it tells you when your Medicare Advantage plan had to tell you, not which day an envelope shows up.3

In Original Medicare with a separate drug plan? Medicare's advice to read your current plan's notices applies to your drug plan too, but the September 30 regulation above covers Medicare Advantage plans only.3

More on reading the letter line by line is in our guide to the Annual Notice of Change.

What Happens If You Do Nothing

Good news on this one: nothing breaks. Medicare's fall guide says that if you've reviewed your options and you're happy with your current coverage, "you don't need to do anything (your coverage will continue automatically)."1

But "do nothing" doesn't mean "nothing changes." If you keep your current Medicare coverage through Open Enrollment, any changes to that plan's benefits or costs for the new year also start on January 1. So staying put is a fine choice, as long as it's a choice you made after reading the notice, not one you slid into.1

Leaving Medicare Advantage for Original Medicare

Say Mom's Medicare Advantage doctor is leaving the network. Medicare Open Enrollment lets someone in a Medicare Advantage Plan switch to Original Medicare, and that change starts January 1 if the request is in by December 7.1

Two things to think through before she makes that move.

Drug coverage. Medicare lists "join, drop, or switch to another Medicare drug plan if you're in Original Medicare" as its own Open Enrollment option, separate from the switch to Original Medicare. If she wants drug coverage after leaving a Medicare Advantage Plan, joining a Medicare drug plan is a separate choice, and that plan must get her enrollment form by December 7. The Part D guide walks through how those plans work.1

Missed Medicare Open Enrollment or Changed Your Mind?

There's a second window, but it's narrower than people assume. The Medicare Advantage Open Enrollment Period runs January 1 through March 31, and it's only for people already enrolled in a Medicare Advantage Plan. During the Medicare Advantage Open Enrollment Period, a Medicare Advantage member can make one change: switch to another Medicare Advantage Plan (with or without drug coverage), or drop the Medicare Advantage Plan and go back to Original Medicare, then join a Medicare drug plan.2

That means Original Medicare enrollees don't get a second shot in January. The Medicare Advantage Open Enrollment Period can't be used to switch from Original Medicare to a Medicare Advantage Plan, to join a Medicare drug plan while in Original Medicare, or to switch from one Medicare drug plan to another while in Original Medicare.2

Those rows come from Medicare's enrollment-periods fact sheet and Section 1851 of the Social Security Act, which limits the January-to-March change to once in each year. For someone new to Medicare who joins a Medicare Advantage Plan, the Medicare Advantage Open Enrollment Period instead runs from the first month they have both Part A and Part B until the last day of the 3rd month they have both. The full rules are in our guide to the Medicare Advantage Open Enrollment Period.2

Outside These Windows: Special Enrollment Periods

Miss both windows and you may still have a way in. Medicare Advantage Plans and Medicare drug plans can be joined, switched, or dropped only during set enrollment periods, but some of those periods open up because of your life, not the calendar. When certain things happen, like a move or losing other coverage, Medicare lets you change your Medicare Advantage Plan or Medicare drug coverage through what it calls a Special Enrollment Period. Which life events count, and how long each one lasts, is in our guide to Medicare Special Enrollment Periods.1

How to Review and Switch, Step by Step

Learn More

Find personalized help deciding what to change during Medicare open enrollment at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.