Medicare Advantage Open Enrollment Period: Dates, Rules and Options

Key Takeaways

The Medicare Advantage open enrollment period runs January 1 to March 31 each year and applies to current Medicare Advantage enrollees only.

During the OEP, you can switch to a different Medicare Advantage plan or return to Original Medicare. Returning to Original Medicare requires a standalone Part D plan for prescription drug coverage.

The OEP is not the Annual Enrollment Period (October 15 to December 7). New enrollees cannot join Medicare Advantage for the first time during the OEP.

Missing the March 31 deadline means you stay on your current plan until the next Annual Enrollment Period opens in October.

What Is the Medicare Advantage Open Enrollment Period?

The Medicare Advantage open enrollment period (OEP) runs January 1 to March 31 each year and permits two actions: switch to a different Medicare Advantage plan or drop Medicare Advantage and return to Original Medicare with a standalone Part D plan. Only current Medicare Advantage enrollees qualify; people joining Medicare for the first time cannot use this window. Any plan switch made during the OEP takes effect the first day of the following month, not immediately. Medicare Advantage plan types such as HMOs and PPOs carry different network and referral rules that affect which switch makes sense for you.

If you're within the January 1 to March 31 window right now, compare plans on Medicare.gov or call 1-800-MEDICARE to review your options. Medicare covers hospital and medical costs under Parts A and B, but plan-level benefits like dental, vision and drug coverage vary by Medicare Advantage plan and are not part of Original Medicare.

THE MEDICARE ADVANTAGE OEP IS NOT THE ANNUAL ENROLLMENT PERIOD

The Annual Enrollment Period runs October 15 to December 7 and is the main window for joining, switching or dropping Medicare Advantage. The OEP (January 1 to March 31) is a secondary window for existing Medicare Advantage enrollees only: new beneficiaries cannot use it to enroll for the first time.

What Can You Do During the Medicare Advantage Open Enrollment Period?

The OEP permits two actions: switch to a different Medicare Advantage plan or drop Medicare Advantage and return to Original Medicare. Enrollees who return to Original Medicare must join a standalone Part D plan for prescription drug coverage, since Original Medicare Parts A and B don't include drug benefits. Any change takes effect the first day of the month after the plan receives the request.

What You Can Do

Switch to a Different Medicare Advantage Plan

You can move from one Medicare Advantage plan to another, including switching plan types such as HMO to PPO. Medicare Advantage HMO plans require a primary care physician and referrals for specialists, while PPO plans allow direct specialist access at higher cost, so confirming the network structure before switching matters as much as comparing premiums.

Return to Original Medicare (Parts A and B)

You can drop your Medicare Advantage plan and return to Original Medicare during this window. Doing so triggers a special enrollment period for a standalone Part D plan, which covers prescription drugs that Original Medicare Parts A and B exclude entirely.

Add or Change a Part D Drug Plan (When Returning to Original Medicare)

Enrollees who return to Original Medicare can simultaneously enroll in a standalone Part D plan before March 31. Missing this deadline means paying out of pocket for prescriptions until the next enrollment opportunity.

Make One Change Per OEP

The OEP allows one plan change only. Plan your comparison before submitting, because you can't reverse the switch with a second OEP action.

What You Cannot Do

Join Medicare Advantage for the First Time

The OEP applies to current Medicare Advantage enrollees only. New Medicare beneficiaries who missed their Initial Enrollment Period or the Annual Enrollment Period cannot use the OEP to enter Medicare Advantage.

Switch from Original Medicare to Medicare Advantage

Moving from Original Medicare into Medicare Advantage for the first time requires the Annual Enrollment Period (October 15 to December 7) or a qualifying Special Enrollment Period. The OEP does not open this path.

Enroll in a Medicare Supplement (Medigap) Plan with Guaranteed Issue

Returning to Original Medicare during the OEP doesn't automatically grant Medigap guaranteed issue rights in most states. Insurers can apply medical underwriting and decline your application based on health status if you're outside a guaranteed issue period.

Check your eligibility before dropping Medicare Advantage. Medicare Supplement plans cover Original Medicare cost-sharing gaps including hospital deductibles and the 20% Part B coinsurance that applies to most outpatient services.

DISCLAIMER

Coverage rules apply to Medicare Advantage plans regulated by CMS. Confirm specific plan availability and actions with your plan or Medicare.gov before making changes.

How Does the Medicare Advantage OEP Compare to Other Medicare Enrollment Windows?

Medicare has four main enrollment windows and each serves a distinct purpose. The OEP is the only one restricted exclusively to current Medicare Advantage enrollees who want to change their plan mid-year. Only one change is permitted per OEP, and it takes effect the first of the following month.

Enrollment Period	Dates	Who Can Use It	Permitted Actions	Effective Date
Medicare Advantage Open Enrollment Period (OEP)	January 1 to March 31	Current Medicare Advantage enrollees only	Switch MA plans or return to Original Medicare; join or change Part D	First day of the month after request is received
Annual Enrollment Period (AEP)	October 15 to December 7	All Medicare beneficiaries	Join, switch, or drop Medicare Advantage; join or change Part D	January 1 of the following year
Initial Enrollment Period (IEP)	3 months before to 3 months after your 65th birthday month	New Medicare-eligible individuals	Enroll in Medicare Parts A, B, C, and D	Varies by enrollment month
Special Enrollment Period (SEP)	Varies by qualifying event	Beneficiaries with a qualifying life event	Varies by event type	Varies by event type

Dates and rules per CMS. Changes made during the OEP take effect the first day of the month after CMS or your plan receives your request. SEP eligibility varies by event type.

The most actionable difference for most readers: if you're unhappy with your Medicare Advantage plan right now and you're within January 1 to March 31, the OEP is your window to act. If you've passed March 31, you'll wait until the Annual Enrollment Period opens in October. Medicare Advantage and Medicare Supplement plans differ in how they handle cost-sharing and network access, which affects whether returning to Original Medicare with a Medigap policy is the better move.

How Can You Enroll in a Medicare Advantage Plan During the OEP?

This process applies to current Medicare Advantage enrollees who want to enroll in a new plan or return to Original Medicare between January 1 and March 31. Before starting, confirm that your intended new plan is available in your county for the current plan year. Coverage under the new plan takes effect the first day of the month after your request is received.

1
Compare Available Medicare Advantage Plans in Your Area
Go to Medicare.gov or call 1-800-MEDICARE (1-800-633-4227) to see which plans are available in your county. Review premiums, deductibles, maximum out-of-pocket limits and drug formularies side by side. Medicare Advantage maximum out-of-pocket limits are capped by CMS each year but vary by plan, so a lower-premium plan may carry a higher out-of-pocket cap that costs more when you actually need care.
2
Confirm the New Plan Covers Your Doctors and Drugs
Check that your primary care physician, specialists, and preferred hospital are in the new plan's network. Confirm your current prescriptions are on the plan's formulary and at an acceptable tier cost. Enrolling in a plan that doesn't cover your medications or providers erases the premium savings.
3
Contact the New Plan Directly or Enroll Through Medicare.gov
You can enroll by calling the new plan directly, visiting Medicare.gov, or calling 1-800-MEDICARE. You don't need to cancel your current plan first. Enrolling in the new plan automatically disenrolls you from the old one, per CMS.
4
Verify Your Coverage Effective Date
Coverage under the new plan starts the first day of the month after your request is processed. If you enroll on February 10, coverage starts March 1. Confirm the effective date in writing before assuming your new coverage is active.
5
Enroll in a Standalone Part D Plan (If Returning to Original Medicare)
If you're returning to Original Medicare, a standalone Part D plan covers prescription drugs that Original Medicare excludes. Part D plans are tiered by drug type and formularies vary by plan, so confirm your specific medications are covered before selecting one. Enroll before March 31 to avoid a gap in drug coverage.

HOW DO YOU SWITCH OR DROP YOUR MEDICARE ADVANTAGE PLAN?

Two routes let you make a plan change during the OEP without canceling your current coverage first.

To switch plans: contact your new Medicare Advantage plan directly or enroll at Medicare.gov. Enrolling in the new plan automatically ends your old one.
To drop Medicare Advantage: call 1-800-MEDICARE or contact your plan to request disenrollment. Request written confirmation that the disenrollment was received.
To confirm the change: coverage under the new plan or Original Medicare begins the first of the month after processing. Verify the effective date before your first appointment.

What Happens If You Miss the Medicare Advantage Open Enrollment Period?

Missing the March 31 deadline means your current Medicare Advantage plan continues unchanged through the rest of the plan year. No penalty applies for staying enrolled. Your next scheduled opportunity to change plans is the Annual Enrollment Period, which opens October 15. One exception exists: a qualifying Special Enrollment Period triggered by a specific life event.

Your Current Plan Continues Automatically

Coverage doesn't lapse if you don't act. Your Medicare Advantage plan rolls over under the same terms until December 31.

Annual Enrollment Period Is Your Next Window

The AEP opens October 15 and lets you switch plans, drop Medicare Advantage, or return to Original Medicare with a January 1 effective date.

A Qualifying Life Event May Open an SEP

Moving out of your plan's service area, losing coverage through no fault of your own or qualifying for Extra Help can trigger a mid-year Special Enrollment Period outside the OEP window.

If you have a qualifying event, you can make changes outside the OEP and AEP windows. Examples include moving to a new county or state where your current plan isn't available or entering or leaving a skilled nursing facility. Contact Medicare at 1-800-MEDICARE or visit Medicare.gov to confirm whether your situation qualifies. The open enrollment period for ACA Marketplace plans runs on a separate calendar with separate qualifying event rules, and does not affect Medicare enrollment windows.

Medicare Advantage Open Enrollment Period: What to Do Before March 31

The Medicare Advantage open enrollment period runs January 1 to March 31, and current enrollees get one change: switch to a different Medicare Advantage plan or return to Original Medicare. If you're returning to Original Medicare, enroll in a standalone Part D plan before March 31 to avoid a drug coverage gap. Act early in the window because changes take effect the first of the month after your request is processed, not the day you submit it.

Frequently Asked Questions

We've answered the most frequently asked questions about Medicare Advantage Open Enrollment Period in 2026:

Can I switch from Original Medicare to Medicare Advantage during the open enrollment period?

No. The Medicare Advantage open enrollment period applies only to current Medicare Advantage enrollees. Switching from Original Medicare to Medicare Advantage requires the Annual Enrollment Period (October 15 to December 7) or a qualifying Special Enrollment Period.

How many times can I change my Medicare Advantage plan during the open enrollment period?

Once. The OEP permits one plan change between January 1 and March 31. A second change isn't possible during the same OEP window. Your next opportunity is the Annual Enrollment Period in October.

What happens to my prescription drug coverage if I switch Medicare Advantage plans?

Most Medicare Advantage plans include prescription drug coverage. When switching plans, confirm your drugs are on the new plan's formulary before completing enrollment. Enrollees who return to Original Medicare instead of switching plans need a standalone Part D plan, which covers drug tiers and formularies that Original Medicare Parts A and B don't include.

Does the Medicare Advantage open enrollment period apply to Medicare Supplement (Medigap) plans?

No. The OEP applies to Medicare Advantage plans only. Medicare Supplement enrollment follows separate rules tied to your Medigap Open Enrollment Period, which is the six-month period that begins the first month you are age 65 or older and enrolled in Medicare Part B. Outside that window, insurers in most states can apply medical underwriting.

Can I use the Medicare Advantage open enrollment period if I have a Special Needs Plan?

Yes. Special Needs Plans (SNPs) are a Medicare Advantage plan type, so current SNP enrollees can switch to a different Medicare Advantage plan or return to Original Medicare during the OEP. SNPs are limited to three eligibility categories defined by CMS: Dual Eligible SNPs (D-SNPs), Chronic Condition SNPs (C-SNPs) and Institutional SNPs (I-SNPs). If switching to a different SNP, confirm you still meet its eligibility requirements before submitting.

What is the difference between the Medicare Advantage open enrollment period and the Annual Enrollment Period?

The Annual Enrollment Period (October 15 to December 7) is open to all Medicare beneficiaries and allows joining Medicare Advantage for the first time, switching plans, or returning to Original Medicare. The OEP (January 1 to March 31) is restricted to current Medicare Advantage enrollees only. AEP changes take effect January 1, while OEP changes take effect the first of the month after the request is received.

About Mark Fitzpatrick

Mark Fitzpatrick, a Licensed Property and Casualty Insurance Producer, is MoneyGeek's resident Personal Finance Expert. He has analyzed the insurance market for over five years, conducting original research for insurance shoppers. His insights have been featured in CNBC, NBC News and Mashable.

Fitzpatrick holds a master’s degree in economics and international relations from Johns Hopkins University and a bachelor’s degree from Boston College. He's also a five-time Jeopardy champion!

He writes about economics and insurance, breaking down complex topics so people know what they're buying.

Read Full Bio »

Medicare Advantage Open Enrollment Period: 2026 Dates & Rules