Medicare Advantage Open Enrollment Period 2026: How to Switch Plans

The Medicare Advantage Open Enrollment Period (MA OEP) runs from January 1 through March 31 every year. During this window, anyone currently enrolled in a Medicare Advantage plan can make one plan change — switch to a different Advantage plan or drop Advantage entirely and return to Original Medicare.

This enrollment period is frequently confused with the Annual Enrollment Period (AEP), which runs October 15 through December 7. They serve different purposes and have different rules. If your parent enrolled in an Advantage plan during the AEP and now regrets the decision — the network is too restrictive, their medications cost more than expected, or their favorite doctor isn't covered — the MA OEP is the window to fix it.

What you can do during the MA OEP

The MA OEP is specifically for people who are already enrolled in a Medicare Advantage plan as of January 1. During this period, your parent can:

1. Switch from one Medicare Advantage plan to a different Medicare Advantage plan — for example, moving from an HMO to a PPO, or from one company's plan to another's
2. Drop Medicare Advantage and return to Original Medicare — which also means they can enroll in a Medigap plan (if they can get one) and a standalone Part D drug plan
3. Switch Medicare Advantage plans and change their drug coverage — since most Advantage plans include Part D, switching plans also changes their drug formulary

Your parent can only make one change during the MA OEP. Once they make a switch, they cannot make another change until the next enrollment period.

What you cannot do during the MA OEP

• You cannot use the MA OEP if you're on Original Medicare. This period is only for people who currently have a Medicare Advantage plan. If your parent is on Original Medicare and wants to join an Advantage plan, they need to wait for the Annual Enrollment Period (October 15 - December 7) or qualify for a Special Enrollment Period.
• You cannot enroll in Medicare for the first time. New Medicare enrollment happens during the Initial Enrollment Period (around their 65th birthday).
• You cannot add or drop standalone Part D coverage unless it's tied to leaving Medicare Advantage for Original Medicare.

When MA OEP changes take effect

Changes made during the MA OEP take effect on the first day of the month after the plan receives the enrollment request. So:

• Enroll in a new plan on January 15 → new coverage starts February 1
• Switch plans on March 10 → new coverage starts April 1
• Make a change on March 31 (last day) → new coverage starts May 1

This is faster than the AEP, where all changes take effect on January 1 regardless of when you enroll.

MA OEP vs. Annual Enrollment Period: the key differences

The AEP is the broader enrollment period where anyone can make changes. The MA OEP is a narrower "second chance" window specifically for Advantage enrollees who want to make an adjustment after seeing how their plan works in the new year.

Why families use the MA OEP

The plan changed and the marketing didn't warn you

Advantage plans can change their benefits, formularies, copay structures, and provider networks every year. The plan your parent enrolled in during the AEP based on 2025 materials may look different when 2026 starts. Common surprises:

• A medication moved to a higher tier — meaning it now costs $50/month instead of $10
• A doctor left the network — requiring your parent to either switch doctors or pay out-of-network rates
• Copays increased for specialist visits, hospital stays, or imaging
• Prior authorization requirements expanded — more services now need pre-approval

The plan sends an Annual Notice of Change (ANOC) in September, but many beneficiaries don't read it or don't understand the implications until they actually try to use the plan in January.

The plan looked good on paper but fails in practice

Some issues only become apparent when your parent starts using the plan:

• The network is thinner than expected — the specialist they need has a 6-week wait, or the nearest in-network hospital is 45 minutes away
• Prior authorizations are denied — a needed procedure or medication is initially rejected
• Customer service is poor — long hold times, confusing explanations, billing errors

The MA OEP exists precisely for these situations. Your parent doesn't have to wait until October to make a change.

Your parent wants to leave Advantage entirely

If your parent's experience with Medicare Advantage has been negative and they want the freedom and predictability of Original Medicare, the MA OEP lets them make the switch. They'd drop the Advantage plan, return to Original Medicare (Parts A and B), and enroll in a standalone Part D drug plan.

The Medigap warning: If your parent leaves Advantage during the MA OEP and wants a Medigap supplement plan, they may face medical underwriting. Medigap guaranteed issue rights (the ability to buy any Medigap plan regardless of health) apply during the first 6 months of Part B enrollment and in certain other specific situations — but not automatically when leaving an Advantage plan after the first year.

If your parent enrolled in Advantage within the past 12 months, they typically have a guaranteed issue right to buy Medigap Plans A, B, C, F, K, or L (but notably, not the most popular Plan G in all states). The rules are state-specific and complex. Before your parent drops Advantage, verify with a Medigap insurer or your state's SHIP program that they can actually get the Medigap plan they want.

Some states (California, Connecticut, Maine, Massachusetts, Missouri, New York, Oregon, and Washington) have more generous Medigap protections that give broader guaranteed issue rights. If your parent lives in one of these states, they may have more flexibility.

How to make a change during the MA OEP

Step 1: Evaluate the problem

Before switching, identify exactly what's not working. Is it the network, the drug formulary, the copay structure, or the overall Advantage model? This determines whether your parent should switch to a different Advantage plan or return to Original Medicare.

Step 2: Compare alternatives

Use the Medicare Plan Finder at Medicare.gov to compare other Advantage plans in your parent's area. Enter their medications and doctors to see which plans offer better coverage at lower cost.

If your parent is considering returning to Original Medicare, price out the combination of Original Medicare + Medigap + Part D to understand the monthly cost difference.

Step 3: Enroll

• To switch Advantage plans: Enroll in the new plan through Medicare.gov, by calling the new plan directly, or through a broker. The old plan is automatically disenrolled when the new one starts.
• To return to Original Medicare: Call the current Advantage plan to disenroll, or enroll in a standalone Part D plan (which automatically switches you from Advantage to Original Medicare). Then apply for Medigap if desired.

Step 4: Confirm the change

After enrollment, verify the change by:

• Checking your parent's coverage on Medicare.gov
• Calling 1-800-MEDICARE to confirm the enrollment
• Contacting the new plan to verify the effective date and that medications and doctors are covered

Don't wait until March 31

While the MA OEP runs through March 31, acting earlier gives your parent more time with better coverage. A switch on January 15 means the new plan starts February 1 — two months of better coverage compared to waiting until late March. If the current plan isn't working, there's no benefit to delaying.

Our Medicare Enrollment Guide includes a plan evaluation checklist, an MA OEP timeline, and a Medigap eligibility reference for families navigating a mid-year plan change — because the January-March window moves quickly when you're also managing a parent's ongoing care.