AEP 2026 Dates: What You Can Do and When

The Medicare Annual Enrollment Period, often called AEP, runs October 15 through December 7, 2026. Any change you make during that window takes effect January 1, 2027. It applies to anyone enrolled in Medicare Advantage or a stand-alone Part D drug plan, or anyone who wants to switch into or out of either. Miss the window, and you generally wait until the next AEP unless you qualify for a separate Special Enrollment Period.

The dates, plainly

October 15, 2026 — AEP opens. You can start making changes on this date.

December 7, 2026 — AEP closes. This is a hard deadline. Changes submitted on or before this date take effect January 1, 2027.

January 1, 2027 — new coverage begins. Whatever plan you're enrolled in as of this date is what covers you for the new plan year, regardless of when during AEP you made the change.

There is no early-bird advantage to enrolling on October 15 versus December 6 in terms of your coverage start date — both take effect January 1. The advantage to acting earlier is practical: more time to compare plans carefully, and less risk of a last-minute mistake or missed deadline. For the official schedule each year, see Medicare.gov's enrollment periods page.

Who AEP is for

AEP applies to a specific set of situations. If any of these describes you, this window is relevant:

You're enrolled in a Medicare Advantage plan and want to switch to a different one. You can move to another Medicare Advantage plan offered in your county.

You're enrolled in Medicare Advantage and want to return to Original Medicare. You can drop Medicare Advantage and go back to Original Medicare, generally pairing it with a stand-alone Part D plan if you want drug coverage.

You're enrolled in Original Medicare and want to switch to Medicare Advantage. The reverse move is also available during this window.

You want to switch stand-alone Part D drug plans. Whether or not you touch your medical coverage, you can change which Part D plan covers your prescriptions.

You want to enroll in a Part D plan for the first time, if you're eligible and didn't previously have drug coverage through another source.

AEP is not the enrollment period for first-time Medicare enrollment when you turn 65 — that has its own separate timeline. It's specifically the annual window for people already on Medicare to review and change their Medicare Advantage or Part D coverage.

What to actually do during AEP

The window itself doesn't require action if nothing about your situation has changed and your current plan still works for you. But it's worth using the time deliberately rather than letting it pass by default. A reasonable approach:

Start with your ANOC letter. Every Medicare Advantage and Part D plan mails an Annual Notice of Change by September 30, ahead of AEP opening. It tells you what's changing about your current plan for the coming year — premium, drug list, network, and out-of-pocket maximum. Read this first; it tells you whether there's a reason to look elsewhere at all.

Check whether your doctors are still in-network, particularly if you've had any indication that a provider might have left your plan's network. Network changes are common and don't always come with a dedicated notice.

Compare your drug costs against other plans, especially if you take regular prescriptions. A plan's premium alone doesn't tell you what you'll pay at the pharmacy; the formulary and tier structure matter just as much.

Decide, and submit the change before December 7. Once you've compared and decided, make the change with enough buffer before the deadline that a processing issue on either end doesn't put you at risk of missing the window.

How AEP is different from other Medicare enrollment windows

Medicare has more than one enrollment window, and it's worth being clear about how AEP relates to the others so you don't confuse them.

The Medicare Advantage Open Enrollment Period, which runs January 1 through March 31, is a separate, narrower window available only to people already enrolled in a Medicare Advantage plan. It allows one plan switch or a return to Original Medicare, but it doesn't allow switching into Medicare Advantage from Original Medicare, and it doesn't apply to standalone Part D changes the way AEP does.

Your Initial Enrollment Period, tied to turning 65, is a separate seven-month window centered on your birthday month and has nothing to do with AEP's calendar dates.

Special Enrollment Periods are triggered by specific qualifying events — a move, losing other coverage, a plan leaving your area — and can happen at any point in the year, independent of AEP.

AEP is the broadest and most commonly used of these windows because it's open to nearly everyone already on Medicare Advantage or Part D, regardless of circumstance, and it allows the widest range of changes. That's also why it tends to get the most attention each fall, and why plans ramp up their own communication to members in the weeks leading up to October 15.

What happens if you miss it

If December 7 passes and you haven't made a change, your current plan continues automatically into the new year — you are not left without coverage. The consequence of missing AEP is narrower than that: you generally cannot switch Medicare Advantage or Part D plans again until the next AEP, roughly a year later, unless you qualify for a Special Enrollment Period in the meantime.

Special Enrollment Periods exist for specific circumstances — certain moves, losing other coverage, a plan leaving your area, and a handful of other defined events. They are not a general substitute for missing AEP; they apply only when your situation matches a recognized triggering event. See Medicare.gov's guide to Special Enrollment Periods for the categories that currently apply. If you're not sure whether your situation qualifies, it's worth checking directly rather than assuming either way.

The bottom line

AEP runs October 15 through December 7, 2026, for coverage that begins January 1, 2027. It's the annual window for anyone on Medicare Advantage or Part D to review their coverage and make a change, whether that means switching plans, switching back to Original Medicare, or adjusting drug coverage. Miss the deadline, and your current plan simply continues — but changing plans again typically has to wait for the next AEP unless a Special Enrollment Period applies to your situation.

For the full official rules on enrollment periods, see Medicare.gov's enrollment periods overview and CMS's Medicare enrollment guidance.