Quick Answer: Medicare Open Enrollment, officially called the Annual Enrollment Period (AEP), runs October 15 through December 7, 2026. During this window, anyone with Medicare can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or add, switch, or drop a Part D prescription drug plan. Any changes you make take effect January 1, 2027. Miss the December 7 deadline, and you’ll generally have to wait until next fall, aside from a narrower Medicare Advantage-only window in January through March.
If you have Medicare, this is the week to pay attention. Medicare Open Enrollment opens October 15 and closes December 7, and it’s the one stretch of the year when you can make a genuinely fresh choice about your coverage, whether that means staying put, switching plans, or moving between Original Medicare and Medicare Advantage entirely.
A lot of people let this window pass without reviewing anything, assuming their current plan will simply carry over unchanged. It will carry over, but it won’t necessarily stay the same. Premiums, drug formularies, and provider networks can all shift year to year, which is exactly why this period exists. Below, I’ll walk through the key dates, what you’re actually allowed to change, and what to do before December 7 arrives.
When Is Medicare Open Enrollment in 2026?
Medicare Open Enrollment, also called the Annual Enrollment Period or AEP, runs from October 15 through December 7, 2026, the same dates every year. Any changes made during this window take effect January 1, 2027, regardless of whether you make the change on October 15 or December 7.
This period is open to anyone with Medicare, not just people enrolling for the first time. Whether you have Original Medicare, a Medicare Advantage plan, a standalone Part D plan, or some combination, AEP is your chance to review and adjust.
Key Dates to Know
- September 30, 2026: Your current plan’s Annual Notice of Change (ANOC) letter should arrive, outlining what’s changing for 2027.
- October 1, 2026: Medicare plan details for 2027 become publicly available.
- October 15, 2026: AEP officially opens; you can begin submitting changes.
- December 7, 2026: AEP closes at 11:59 PM local time. This is a hard deadline.
- January 1, 2027: Any changes made during AEP take effect.
What Can You Change During Medicare Open Enrollment?
During AEP, you can switch from Original Medicare to a Medicare Advantage plan, or move from Medicare Advantage back to Original Medicare. You can switch from one Medicare Advantage plan to a different one, or enroll in, switch, or drop a standalone Part D prescription drug plan. You can make as many changes as you want during the window; only your final submission before December 7 takes effect.
What AEP doesn’t cover is enrolling in Medicare itself for the first time, or purchasing a Medigap policy, both of which follow their own separate rules and timelines.
A Trade-Off Worth Understanding
Reviewing your coverage every year takes a little effort, and it’s tempting to skip it if your current plan has treated you fine. But “fine last year” and “still the best fit this year” aren’t always the same thing. Premiums creep up, formularies shift which drugs are covered and at what tier, and provider networks change which doctors are in-network. The cost of skipping the review is usually invisible until a claim or a pharmacy bill tells you otherwise.
How Is AEP Different From the Medicare Advantage Open Enrollment Period?
These two windows get confused constantly, and the mix-up can cost people a missed opportunity. AEP, October 15 through December 7, is open to anyone with Medicare and allows unlimited changes across Original Medicare, Medicare Advantage, and Part D.
The Medicare Advantage Open Enrollment Period (MA-OEP), January 1 through March 31, is narrower. It’s only available to people already enrolled in a Medicare Advantage plan, and it allows just one change: switching to a different Medicare Advantage plan or dropping Advantage to return to Original Medicare. If you have Original Medicare only, the January-to-March window doesn’t apply to you at all.
A Real Scenario Worth Considering
Say you’re on Medicare Advantage in Tulsa and you miss AEP entirely this fall. You’re not completely out of options. Come January 1, the MA-OEP opens and gives you one more chance to switch plans or move back to Original Medicare before March 31. But if you have Original Medicare and wanted to add or change a Part D plan, that January window won’t help you; you’d be waiting until next October instead.
What Should You Do Before December 7?
Start with your ANOC letter. It outlines exactly what’s changing about your current plan for next year, including premium, deductible, and formulary changes, and it’s usually the fastest way to tell whether your plan still fits. From there, confirm your doctors and pharmacies are still in-network, check your medications against the plan’s updated formulary, and compare your total expected costs, not just the premium, against your other options.
AEP is your once-a-year window to switch, and waiting until December 6 to start looking rarely ends well. This is exactly the kind of review I help clients across the Tulsa area work through every fall. If you’d like a second set of eyes on your current plan before the deadline, you can schedule a free consultation and we’ll go through your options together.
Frequently Asked Questions
When is Medicare Open Enrollment 2026?
Medicare Open Enrollment, or the Annual Enrollment Period, runs from October 15 through December 7, 2026. Changes made during this window take effect January 1, 2027.
What can I change during Medicare Open Enrollment?
You can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, or add, switch, or drop a Part D prescription drug plan.
What happens if I miss the December 7 deadline?
You’ll generally need to wait until the next Annual Enrollment Period the following October, unless you have a Medicare Advantage plan and qualify for the narrower January-to-March Medicare Advantage Open Enrollment Period.
Is Medicare Open Enrollment the same as the Medicare Advantage Open Enrollment Period?
No. AEP (October 15 to December 7) is open to anyone with Medicare for unlimited changes. The Medicare Advantage Open Enrollment Period (January 1 to March 31) is only for people already in a Medicare Advantage plan and allows just one change.
Do I need to do anything if I’m happy with my current plan?
It’s still worth reviewing your Annual Notice of Change letter, since premiums, formularies, and provider networks can shift even if you don’t make any changes yourself.
The Bottom Line
Medicare Open Enrollment comes down to one window, October 15 through December 7, 2026, and one hard deadline. Whether you end up switching plans or deciding your current coverage is still the right fit, the only way to know for sure is to actually review it before the window closes.
AEP is your once-a-year window to switch. Call 918-815-6382 or schedule a free consultation and book your plan review before December 7. You can also browse our Medicare plan options or read our Medicare frequently asked questions for more detail.