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Medicare Advantage OEP 2026: Dates, Rules and Your Next Move

Bend resident compares Medicare Advantage plan options

The Medicare Advantage Open Enrollment Period (OEP) runs January 1 to March 31 each year, and it is only for people already in a Medicare Advantage plan. The 2026 window has closed. The next one opens January 1, 2027. If you are reading this in late October 2026, the window that matters right now is different: the fall Open Enrollment, which runs October 15 to December 7, 2026, with changes starting January 1, 2027.

People mix these two up all the time, and the mix-up costs real money. Below, we explain how each period works, who can use it, and how to decide what to do. We are a local agency in Bend, Oregon, so we also cover what Central Oregon readers should check first.

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TL;DR

  • Medicare Advantage OEP: January 1 to March 31. You must already have a Medicare Advantage plan, and you get one change only.
  • Fall Open Enrollment: October 15 to December 7, 2026. Anyone can join, switch or drop a Medicare Advantage or drug plan, effective January 1, 2027.
  • Today is October 22, 2026, so the fall window is open now and the January OEP is your backup, not your plan A.
  • Oregon Medigap holders may have a separate tool, the Birthday Rule, to switch supplement policies without health questions.
  • Before you switch anything, confirm your doctors, pharmacy and drugs on the new plan’s list for 2027.

Table of Contents

Two windows, two sets of rules

Medicare gives you more than one chance a year to change Part C and Part D coverage, and they are not interchangeable. Here is the side-by-side.

Fall Open Enrollment (AEP) Medicare Advantage OEP
Dates October 15 to December 7 January 1 to March 31
Who can use it Anyone with Medicare Only people already in a Medicare Advantage plan
What you can do Join, switch or drop a Medicare Advantage or Part D plan Switch to another Medicare Advantage plan, or return to Original Medicare
How many changes Your last valid choice counts One change only
When coverage starts January 1 First of the month after the plan gets your request

The fall dates and the January 1 start come from Medicare.gov’s Open Enrollment page. The OEP details, including the one-change limit and the first-of-the-month start, are laid out in Medicare’s guide to Part C and Part D enrollment periods.

One point trips up many readers. The OEP lets you leave Medicare Advantage for Original Medicare, and you can add a standalone drug plan at the same time. It does not let you pick a Medigap supplement with guaranteed acceptance. We come back to that below, because it is the biggest trap in the January window.

Why the OEP “2026” and the fall window get confused

Much of what you see online about “2026 open enrollment” describes the fall period of 2025. That period ran October 15 to December 7, 2025, and set up your 2026 coverage, as the CMS announcement on 2026 plans explains. The OEP in January to March 2026 was the follow-up window for people who were unhappy with the plan they had just started.

So the calendar looks like this for a person with Medicare Advantage:

  1. October 15 to December 7, 2026: review your 2027 plan, and change it if it no longer fits.
  2. January 1, 2027: the plan year starts. Your new or renewed plan takes effect.
  3. January 1 to March 31, 2027: if the plan you are in turns out to be wrong, you get one switch.

The lesson: the fall window is the one to use deliberately. The OEP is a safety net. Use it too casually and you spend your single change.

What to review before December 7

Every September, your plan mails an Annual Notice of Change. Many people toss it. Read it. Plans can alter premiums, copays, drug lists and networks from one year to the next. Here is the order we suggest.

1. Your doctors and hospitals

Medicare Advantage plans use networks. Experts who follow the market tell people to confirm that their specific doctors and pharmacies remain in-network before they change anything, as noted in KFF’s analysis of Medicare Advantage in 2026. In Central Oregon, where specialists can be a drive away, a plan that looks cheap but drops your orthopedist is not cheap. We walk through how to check in our guide to confirming your doctors in Medicare Advantage networks.

2. Your prescriptions

List every drug, the dose and your pharmacy. Then check each one against next year’s drug list and its tier. The Part D out-of-pocket cap was $2,100 in 2026, as we explain in our breakdown of the Part D cap. The 2027 figures and any deductible changes should be checked in the plan documents, not assumed. If a weight loss medication is on your list, read up on Medicare coverage of weight loss drugs first, since coverage rules for that category differ from ordinary prescriptions. Our page on the Part D deductible covers how the deductible works.

3. Total yearly cost, not just the premium

A $0 premium plan can still charge you at the doctor, the hospital and the specialist. Look at four numbers together: the monthly premium, the deductible, the copays for your usual care, and the plan’s yearly out-of-pocket maximum. Medicare Advantage plans set their own maximums, while Original Medicare has no set limit, per Medicare’s cost overview.

For reference, that same page lists the 2026 standard Part B premium at $202.90 a month and the Original Medicare deductible at $283. Part B is paid on top of any Medicare Advantage premium. For a deeper look at it, see our Part B premium explainer. CMS projected that the average Medicare Advantage premium would fall from $16.40 in 2025 to $14.00 in 2026, according to the same CMS release. Our post on Medicare Advantage premiums goes further into what $0 really means.

4. Extras and rules for approval

Dental, vision and hearing allowances vary widely. So does prior authorization, the plan’s requirement that it approve certain care before you get it. KFF’s report covers both supplemental benefits and prior authorization, and it is worth skimming before you sign. Special Needs Plans have also been taking a larger share of enrollment growth, per the same KFF material, so if you have a chronic condition or Medicaid, ask whether one applies to you.

Worked example: one change, two outcomes

Take a hypothetical couple in Bend, both on the same Medicare Advantage plan. In November they skip the Annual Notice of Change. On January 1 they learn that the plan’s network no longer includes the clinic one of them uses. In February, one spouse uses the OEP to move to a different plan. That works, but it is the spouse’s only change until the next fall window, and each spouse has their own change. If the new plan’s drug list also misses a medication, there is no second try, barring a special circumstance.

Now the same couple, same problem, caught in October. They compare three plans against their doctors and drugs, pick one, and enroll before December 7. Their single OEP change is still available in case something unexpected happens in January. Same couple, same plan, very different year.

October review versus January OEP change

Leaving Medicare Advantage for Original Medicare: read this first

Some people use the OEP or the fall window to go back to Original Medicare. The mechanics are simple. The catch is the supplement.

When you return to Original Medicare, you usually want a Medigap policy to cover what Parts A and B leave behind. Under federal rules, you generally do not have a right to buy a Medigap policy, or to switch policies, unless you are in your six-month Medigap open enrollment period or have a specific guaranteed issue right, as Medicare explains. In many states that means an insurer can ask health questions or decline you. Before you drop your Medicare Advantage plan, find out whether you could qualify for a Medigap policy. If you cannot, staying put may be the safer move. Our post on the Medicare Advantage disenrollment period covers the one-change rule in more detail.

Oregon’s Birthday Rule: for people already on Original Medicare

If you already have a Medigap policy and your rates keep climbing, Oregon has an unusual tool. The state’s Birthday Rule lets you move to another Medigap policy with the same or lesser benefits once a year, in the window that starts 30 days before your birthday and ends 30 days after it, without being turned down for your health. The details are in the Oregon Division of Financial Regulation fact sheet.

Three cautions from the state’s own guidance:

  • Do not cancel your current policy until the new one is issued. You may have to pay two premiums for one month, because mid-month effective dates are discouraged and insurers typically require notice. The SHIBA Birthday Rule fact sheet says so directly.
  • The rule applies to Medigap, not Medicare Advantage. It does not give you extra time in the fall or January windows.
  • Switching a Plan F high-deductible policy to another carrier restarts the deductible, per the state fact sheet.

The fact sheets are dated 2023, so confirm the current wording with Oregon’s insurance division or a licensed agent before acting. If this might be you, our Medicare Supplement plans page is a good place to start.

Our perspective: slow down, and use the January window as a net

We talk to Central Oregon seniors every fall, and the same pattern repeats. Someone gets a postcard or a phone call with a big promise, picks a plan in ten minutes, and finds out in February that a doctor or drug is not covered. The plan was not necessarily bad. The check was missing.

Our perspective: slow down, and use the January window as a net — overview diagram

Our advice is plain. Treat October 15 to December 7 as your decision window, and finish by early December so a mistake in paperwork does not cost you. Treat the January to March OEP as insurance against surprises, not as a second chance you can plan on. If you are not sure whether you are in the right plan, a review in November is far cheaper than a bad February.

We also believe you should understand a plan before you enroll in it. That is why our consultations are educational first. We are paid by carriers when a client enrolls, and the consultation costs you nothing, but we would rather you leave informed and keep your current plan than switch for the wrong reason.

— Jesse Zimmerman

Get a free review before December 7

If you want a second set of eyes on your 2027 options, we offer free in-person and remote consultations for Central Oregon residents. We can compare your current plan against others by your doctors, drugs and budget, and we can handle the enrollment if you decide to change. Start with our annual Medicare plan review, or see our Medicare Advantage plans in Bend. If you are new to Medicare and need help signing up, our enrollment assistance page explains how we work.

You can also get free, unbiased counseling from Oregon’s state program. SHIBA’s certified counselors answer Medicare questions, and you can find local Medicare help through SHIBA or call 800-722-4134.

A short checklist for the next six weeks

  1. Find your Annual Notice of Change and read the first page.
  2. Write down every doctor, specialist, hospital and pharmacy you use.
  3. List your drugs, doses and how often you fill them.
  4. Compare your current plan with at least two others on total yearly cost.
  5. Check each plan’s prior authorization rules for the care you expect to need.
  6. Enroll before December 7, and keep confirmation in writing.
  7. In January, use your new cards and fill a prescription. If something fails, remember you have one OEP change through March 31.

For related dates, see our Medicare AEP guide, the overview of Medicare enrollment periods, and our Central Oregon OEP deadline post.

FAQ

When is the Medicare Advantage Open Enrollment Period?

It runs every year from January 1 to March 31. Only people already enrolled in a Medicare Advantage plan can use it. The 2026 window has passed, and the next one starts January 1, 2027.

Can I switch to a Medigap plan during the Medicare Advantage OEP?

You can leave Medicare Advantage for Original Medicare, but that does not guarantee you a Medigap policy. In most cases you need to be in your Medigap open enrollment period or have a guaranteed issue right, so ask before you drop your plan. Oregon’s Birthday Rule helps only if you already hold a Medigap policy.

How many times can I change plans during the OEP?

Once. You can switch to a different Medicare Advantage plan or return to Original Medicare, and the change takes effect the first of the month after the plan receives your request. After that you wait for the next fall window unless a special circumstance applies.

Is the fall Open Enrollment the same as the OEP?

No. The fall period, October 15 to December 7, is open to everyone with Medicare and covers Medicare Advantage and drug plans, with changes starting January 1. The OEP is a smaller January to March window for people already in Medicare Advantage.

Sources

Disclaimer: This article is for general educational purposes only and does not constitute personalized advice. Medicare rules and plan details change frequently.

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