Medicare AEP vs. OEP: Understanding the Medicare Enrollment Periods

Medicare's Annual Enrollment Period (AEP) and Medicare Advantage Open Enrollment Period (MA OEP) both give eligible beneficiaries opportunities to change Medicare coverage, but they serve different purposes and follow different rules.

For the upcoming plan-year transition:

• Medicare AEP: October 15–December 7, 2026
• AEP coverage effective date: Generally January 1, 2027
• Medicare Advantage OEP: January 1–March 31, 2027
• MA OEP effective date: Generally the first day of the month after the plan receives the enrollment request

For Medicare agents, the easiest way to remember the difference is:

AEP is the broad annual opportunity to review and change Medicare health and drug coverage. MA OEP is a narrower opportunity for eligible Medicare Advantage enrollees to make one change.

OEP is not a second AEP.

Understanding that distinction can help agents explain enrollment options accurately, identify the correct election period, and avoid creating expectations that a client can make a change when no applicable enrollment period is available.

Medicare AEP vs. OEP at a Glance

If you need a refresher on Initial Enrollment Periods, Special Enrollment Periods, and other Medicare enrollment windows, see PSM's Medicare Enrollment Periods Explained.

What Is the Medicare Annual Enrollment Period?

The Medicare Annual Enrollment Period runs from October 15 through December 7 every year.

Medicare.gov calls this period Medicare Open Enrollment. Insurance agents also commonly refer to it as AEP.

During AEP, beneficiaries generally have their broadest annual opportunity to review and change Medicare Advantage and prescription drug coverage.

Depending on their circumstances, a beneficiary may:

• Switch from Original Medicare to a Medicare Advantage plan.
• Switch from Medicare Advantage back to Original Medicare.
• Move from one Medicare Advantage plan to another.
• Join a Medicare prescription drug plan.
• Switch Medicare prescription drug plans.
• Drop Medicare prescription drug coverage when permitted.

Changes made during Medicare Open Enrollment generally become effective January 1 of the following year.

When is Medicare AEP for 2027 coverage?

For beneficiaries choosing coverage for the 2027 plan year:

AEP begins October 15, 2026, and ends December 7, 2026.

A valid plan change made during that period generally takes effect January 1, 2027.

Agents preparing for this enrollment season can use PSM's 2027 AEP Preparation Guide for Agents for a broader preparation framework covering client reviews, workflows, compliance, training, marketing, and technology.

What Should Agents Review During AEP?

AEP should be about more than comparing a premium or highlighting one attractive benefit.

Plan details can change from one year to the next, and a client's needs can change as well. A useful annual review may include:

Provider access

Confirm whether the client's important physicians, specialists, hospitals, and other providers participate in the plan's network for the new plan year.

Do not assume a provider's participation remains unchanged.

Prescription drugs

Review the client's current medications and consider:

• Formulary status.
• Drug tiers.
• Preferred pharmacies.
• Prior authorization.
• Step therapy.
• Quantity limits.
• Applicable prescription drug costs.

Costs

Review the costs most relevant to the client's anticipated use of coverage, including:

• Monthly premiums.
• Deductibles.
• Copayments.
• Coinsurance.
• Maximum out-of-pocket limits when applicable.

Plan rules

Make sure the client understands relevant requirements involving:

• Provider networks.
• Referrals.
• Prior authorization.
• Out-of-network coverage when applicable.

Supplemental benefits

If dental, vision, hearing, transportation, over-the-counter allowances, or other supplemental benefits are important to the client, verify the current plan-year details, limitations, eligibility requirements, and service-area availability.

Benefits vary by plan and market.

Use the Annual Notice of Change as a Starting Point

Clients who are already enrolled in Medicare Advantage or Part D coverage receive plan information describing changes for the coming year.

The Annual Notice of Change (ANOC) can help identify changes involving costs, coverage, service areas, provider networks, drug coverage, and other plan provisions.

For agents, the ANOC is a starting point—not a substitute for a complete needs analysis.

A client whose existing plan changes very little may still have different health care priorities, prescriptions, providers, or financial considerations than they had a year earlier.

Likewise, a plan with significant changes is not automatically the wrong plan. The appropriate coverage decision depends on the individual beneficiary's circumstances and available options.

What Is the Medicare Advantage Open Enrollment Period?

The Medicare Advantage Open Enrollment Period runs from January 1 through March 31 each year.

Unlike AEP, the annual MA OEP is primarily for beneficiaries who are already enrolled in a Medicare Advantage plan.

During MA OEP, an eligible beneficiary can generally make one change.

They may:

• Switch from one Medicare Advantage plan to another Medicare Advantage plan, with or without prescription drug coverage, or
• Leave Medicare Advantage and return to Original Medicare.

When a beneficiary leaves Medicare Advantage and returns to Original Medicare during MA OEP, they can generally also join a stand-alone Medicare drug plan when applicable.

The coverage change generally becomes effective on the first day of the month after the plan receives the enrollment request.

For a deeper discussion of the enrollment rules, client review process, marketing restrictions, and agent workflow, see PSM's Medicare Open Enrollment Period: Rules, Dates & Checklist.

What Can't a Client Do During Medicare Advantage OEP?

This is where agents need to be especially careful.

MA OEP is not a second Annual Enrollment Period.

During the annual Medicare Advantage OEP, a beneficiary generally cannot use the OEP to:

• Move from Original Medicare into a Medicare Advantage plan.
• Join a stand-alone Medicare drug plan while remaining in Original Medicare solely because MA OEP is open.
• Switch from one stand-alone Part D plan to another using MA OEP.
• Make repeated Medicare Advantage plan changes throughout January, February, and March.

If MA OEP does not allow the desired change, determine whether another valid enrollment period—such as a Special Enrollment Period—applies to the beneficiary's circumstances.

AEP vs. OEP: A Simple Client Example

Consider a client who is currently enrolled in Medicare Advantage.

During AEP

In November 2026, the client reviews their 2027 coverage options.

During AEP, they may have several choices available, including remaining in their current plan, changing Medicare Advantage plans, or returning to Original Medicare. They may also have applicable Part D options.

A valid AEP election generally becomes effective January 1, 2027.

During OEP

Now suppose the same beneficiary starts using their 2027 Medicare Advantage coverage in January and discovers that the coverage does not work as expected.

Because the beneficiary is already enrolled in Medicare Advantage, MA OEP may permit one change between January 1 and March 31.

The client could potentially switch to another Medicare Advantage plan or return to Original Medicare, subject to the applicable rules.

That's the practical difference:

AEP provides broad annual choice. OEP provides a limited Medicare Advantage correction window.

Why Might a Client Contact an Agent During OEP?

Once new coverage begins January 1, clients may discover issues they did not anticipate during AEP.

Common questions may involve:

• A doctor or specialist not participating in the network.
• A prescription being covered differently than expected.
• A pharmacy not being preferred or participating as expected.
• Unexpected copayments or coinsurance.
• Prior authorization requirements.
• Referral requirements.
• Difficulty understanding or accessing supplemental benefits.
• Confusion about how the plan works.

The first response should not automatically be a plan change.

Sometimes the best service an agent can provide is helping a client understand how to properly use their current coverage.

When the coverage itself does not meet the client's needs, the agent can then determine whether MA OEP or another valid enrollment period permits a change.

Be Careful When a Client Wants to Leave Medicare Advantage

A beneficiary may use MA OEP to return to Original Medicare, but that decision can raise another important question:

What happens to Medicare Supplement coverage?

Returning to Original Medicare does not automatically mean a beneficiary will be able to purchase any Medigap policy they want without medical underwriting.

Federal guaranteed-issue protections apply in certain circumstances, and additional protections can differ by state.

Before treating an MA-to-Original-Medicare transition as a simple coverage change, agents should consider:

• Whether the client has a Medigap guaranteed-issue right.
• Applicable state rules.
• Available Medicare Supplement policies.
• Possible underwriting requirements.
• Prescription drug coverage needs.
• Effective dates.
• Timing between the different coverages.

Agents looking to strengthen their understanding of the two major coverage approaches can also review PSM's Medicare Advantage vs. Medicare Supplement training resource.

Is There an OEP for People Who Are New to Medicare?

Yes. There is a separate Medicare Advantage OEP opportunity for certain beneficiaries who are new to Medicare and initially enroll in Medicare Advantage.

If an individual joins Medicare Advantage during their initial Medicare enrollment opportunity, they generally have an opportunity to switch to another Medicare Advantage plan or return to Original Medicare during the first three months they have both Medicare Part A and Part B.

This timing is based on the beneficiary's individual Medicare effective dates rather than the standard January 1–March 31 calendar window.

Because the dates can vary from one beneficiary to another, agents should confirm the applicable election period before submitting an enrollment request.

AEP and OEP Require Different Agent Strategies

The enrollment rules are different, and the agent's approach should be different as well.

During AEP: prepare for comprehensive annual reviews

AEP is the appropriate period for broad annual plan reviews and permitted plan-change discussions.

Agents should prepare by:

• Completing required annual certifications.
• Reviewing carrier and product updates.
• Organizing their existing book of business.
• Reviewing client information before appointments.
• Confirming enrollment and quoting technology is ready.
• Reviewing current compliance requirements.
• Preparing approved marketing and educational materials.
• Establishing follow-up workflows.
• Planning enough time for accurate plan comparisons.

PSM's 2027 AEP Preparation Guide provides a more detailed checklist for independent Medicare agents preparing for the season.

During OEP: focus on responsive client service

MA OEP should not be approached as another unrestricted AEP sales season.

Instead, agents should be prepared to respond appropriately when an eligible beneficiary has questions or proactively asks for assistance.

That may mean:

1. Understanding why the client is dissatisfied.
2. Reviewing the client's existing coverage.
3. Determining whether the problem can be resolved without changing plans.
4. Confirming whether the client has a valid enrollment period.
5. Comparing available coverage when appropriate.
6. Reviewing the consequences of a change.
7. Documenting the interaction and election correctly.

Medicare OEP Marketing Rules Agents Should Know

The Medicare Advantage OEP has specific marketing restrictions.

Current federal regulations prohibit Medicare Advantage organizations from knowingly targeting or sending unsolicited marketing materials to MA enrollees during OEP.

The regulations also prohibit activities designed to specifically target beneficiaries in OEP because of an AEP decision or promote agent and broker activity intended to treat OEP as another opportunity to generate sales.

At the same time, the rules allow certain beneficiary-initiated activity.

For example, an MA organization may:

• Provide marketing materials when a beneficiary proactively requests them.
• Conduct a one-on-one meeting with a sales agent at the beneficiary's request.
• Provide OEP information through a call center when requested.
• Include educational, non-marketing information about the existence of OEP on its website.

For agents, the practical distinction is:

Be available to serve beneficiaries who request assistance, but do not treat OEP as an unrestricted prospecting campaign.

Agents should review current CMS requirements, applicable carrier guidance, consent requirements, and their organization's compliance procedures before distributing Medicare marketing or conducting enrollment activity.

For a deeper treatment of these rules, use PSM's Medicare OEP agent guide.

Common AEP and OEP Mistakes Agents Should Avoid

1. Treating OEP like a second AEP

The January 1–March 31 MA OEP is narrower than AEP. It does not give every Medicare beneficiary another broad opportunity to reconsider coverage.

2. Assuming everyone can use OEP

The annual MA OEP is primarily for beneficiaries already enrolled in Medicare Advantage.

Always determine the client's current coverage before discussing available elections.

3. Overlooking effective dates

AEP changes generally take effect January 1.

MA OEP changes generally take effect the first day of the month after the plan receives the request.

The difference can affect how agents explain coverage transitions.

4. Changing plans before identifying the real problem

A dissatisfied client may need help understanding their existing plan rather than replacing it.

Investigate the client's concern before assuming a change is necessary.

5. Overlooking Medigap implications

Leaving Medicare Advantage does not guarantee unrestricted access to Medicare Supplement coverage.

Review federal and state Medigap protections and any applicable underwriting requirements before the client makes a decision.

6. Using outdated plan information

Benefits, formularies, provider participation, premiums, and other plan details can change.

Use current plan-year information and verify market availability.

7. Treating a best practice as a CMS requirement

Separate federal requirements, carrier rules, agency procedures, and operational best practices.

When uncertain, verify the current source before advising a client or changing your workflow.

AEP and OEP Agent Checklist

Before discussing a Medicare plan change, ask:

• What coverage does the client have now?
• Which enrollment period applies?
• What change does that enrollment period permit?
• Has the client already used the available election?
• What is the effective date of the proposed change?
• Have current providers been verified?
• Have current prescriptions and pharmacy preferences been reviewed?
• Have relevant costs and plan rules been reviewed?
• Are plan details current for the applicable service area and plan year?
• Could changing coverage affect Medigap eligibility or underwriting?
• Are current CMS and carrier requirements being followed?

That simple workflow can prevent many of the most common enrollment-period misunderstandings.

Frequently Asked Questions About Medicare AEP vs. OEP

When is Medicare AEP in 2026?

Medicare AEP runs October 15 through December 7, 2026. Elections made during AEP generally become effective January 1, 2027.

When is Medicare Advantage OEP in 2027?

The annual Medicare Advantage Open Enrollment Period runs January 1 through March 31, 2027 for eligible beneficiaries already enrolled in Medicare Advantage.

Can a client switch Medicare Advantage plans during OEP?

Yes. An eligible beneficiary can generally make one change during the annual Medicare Advantage OEP, including switching from one Medicare Advantage plan to another.

Can someone with Original Medicare join Medicare Advantage during OEP?

Not by using the annual Medicare Advantage OEP. Someone in Original Medicare generally needs another valid enrollment period, such as AEP or an applicable Special Enrollment Period, to enroll in Medicare Advantage.

Can a client go back to Original Medicare during OEP?

Yes. An eligible Medicare Advantage enrollee may leave Medicare Advantage and return to Original Medicare during MA OEP. The beneficiary may also be able to enroll in stand-alone Part D coverage when applicable.

Agents should also evaluate potential Medigap implications before the change is made.

Can a client change plans more than once during OEP?

The annual Medicare Advantage OEP generally permits one change.

Is AEP the same as Medicare Open Enrollment?

Medicare.gov refers to the October 15–December 7 period as Medicare Open Enrollment. Within the Medicare insurance industry, agents commonly call the same period the Annual Enrollment Period, or AEP.

That terminology can create confusion because the Medicare Advantage Open Enrollment Period is a separate January 1–March 31 enrollment window.

What if a client cannot use AEP or OEP?

The client may qualify for a Special Enrollment Period (SEP) based on a specific circumstance.

SEPs can result from events such as certain moves, loss of qualifying coverage, changes in Medicaid or Extra Help status, institutional status, and other circumstances defined by Medicare.

Each SEP has its own eligibility requirements, timing, and permitted elections, so agents should verify the specific SEP before submitting an application.

For an overview of the major Medicare enrollment windows, see Medicare Enrollment Periods Explained.

Prepare for AEP and OEP With PSM Brokerage

Knowing the enrollment dates is only one part of running a Medicare business.

Independent agents also need current product information, contracting support, training, compliant marketing resources, quoting and enrollment technology, and reliable back-office assistance.

PSM Brokerage supports independent Medicare agents with resources designed to help them prepare for enrollment season and serve clients throughout the year.

Explore PSM's Medicare agent resources, work through the 2027 AEP Preparation Guide, or learn more about what to look for in a Medicare FMO.

Ready to strengthen your Medicare business while maintaining your independence? Explore PSM Brokerage's Medicare resources and agent support.

For agent use only. This article is educational and is not legal advice. Medicare enrollment, marketing, carrier, state, and plan requirements may change. Agents should verify current requirements with CMS, Medicare.gov, applicable carriers, state regulators, and their compliance resources before acting.