Understanding Enrollment Periods (AEP, GEP, OEP, IEP, SEP)

Understanding Medicare enrollment periods is crucial for helping clients select and maintain the proper coverage. This overview clearly explains each enrollment window, how it works, and what clients can and cannot do during each period. Use this to guide conversations, set expectations, and support informed decision-making.

Annual Election Period (AEP)

Dates: October 15 – December 7

Available to all Medicare beneficiaries to join, switch, or drop a MA, MAPD, and PDP plan available for the upcoming calendar year.

Beneficiaries can stay on their current plan if it remains available or use AEP to explore and move to a plan that better meets their needs.

Plan enrollments done during AEP will take eﬀect January 1st of the following year.

If a beneficiary joins a Medicare Advantage Plan during this period but changes their mind, they can switch back to Original Medicare or enroll in a different Medicare Advantage Plan (depending on which coverage works better for them) during the Medicare Advantage Open Enrollment Period (January 1st-March 31st).

Effective Date:
All AEP changes take effect on January 1 of the following year.

❗Important:

Only CMS-approved materials for the upcoming plan year may be used.
All communication must follow CMS marketing and compliance rules.

General Enrollment Period (GEP)

Dates: January 1 – March 31

GEP applies to beneficiaries who've missed their 7-month IEP and don't qualify for an SEP.

Coverage for an individual's Part B begins on the first day of the month after they enroll. (For example, if an individual selects to pick up their Part B in January, it will be eﬀective February 1st.)

Those with Part A who have selected Part B during their GEP may elect to enroll in an MA, MAPD, or PDP prior to the effective date of their Part B and for two months following the month of eligibility.

Example: If I enroll in Part B on 3/16 with an effective date of 4/1, I will have all of March, April, and May to enroll in an MAPD/PDP, and it will be effective the first of the month following the election. If I decide to enroll in an MAPD on 5/17, it will be effective 6/1.

Effective Date:
Changes generally take effect on the first day of the month after the enrollment request, helping agents explain timing clearly to clients.

Medicare Advantage Open Enrollment Period (OEP)

Dates: January 1 – March 31

MA OEP is available to all Medicare beneficiaries on MA or MAPD plans. It allows them to select a diﬀerent plan or return to Original Medicare. Beneficiaries can only make one change during this period.

They can make a one-time enrollment during the first three (3) months of the calendar year to switch MA/MAPD plans or disenroll from an MA plan and obtain coverage through Original Medicare.

Plan enrollments made during the MA OEP will take effect on the first day of the month following the month of enrollment.

The following changes are not permitted:

✅Switching from Original Medicare to an MA Plan.

✅Joining a Medicare Prescription Drug Plan if they are in Original Medicare.

✅Switching from one Medicare Prescription Drug Plan to another.

Effective Date:
Changes generally take effect on the first day of the month after the enrollment request, helping agents explain timing clearly to clients.

Initial Enrollment Period (IEP)

IEP is the first time a beneficiary becomes eligible to enroll in a MAPD plan.

A beneficiary may enroll in MAPD during IEP if:

They have Medicare Part A and Part B
They live in the MAPD plan’s service area

IEP for Individuals Turning 65

A seven-month window:

Starts three months before the beneficiary’s 65th birthday month
Includes the birth month
Ends three months after the birth month

MAPD effective dates depend on when the request is submitted within this window.

IEP for Individuals First Enrolling in Part B After Age 65 (IEP2)

For individuals who delayed Part B:

Starts three months before the Part B effective date
Includes the Part B start month
Ends three months after the start month

This provides a one-time MAPD enrollment opportunity linked to Part B activation.

Special Enrollment Periods (SEPs)

SEPs allow beneficiaries to make MAPD enrollment changes outside of AEP, OEP, or IEP when certain qualifying events occur.

Common MAPD SEPs include:

Moving into, out of, or within a MAPD service area
Losing certain types of health coverage (e.g., employer or union coverage)
Gaining or losing eligibility for Medicaid or specific low-income programs
Entering, residing in, or leaving specific institutional settings
During the "Government Entity-Declared Disaster or Other Emergency" SEP
Becoming eligible for a Chronic Condition Special Needs Plan (C-SNP)
Plan non-renewal or plan termination

SEP Effective Dates:
Most SEP elections take effect on the first day of the month after the enrollment request, unless CMS specifies otherwise.

Government Entity-Declared Emergency SEPs end two full calendar months after the end date identified in the declaration or, if different, the date the incident is announced to have ended, whichever is later.

❗Agents must document the correct SEP and ensure the beneficiary qualifies.

Remember

When enrolling clients:

Confirm that the beneficiary is eligible for the enrollment period being used
Document SEP usage when required
Use only CMS-approved MAPD marketing materials
Ensure the beneficiary understands their options
Follow CMS marketing and communication guidelines
Avoid submitting MAPD enrollments outside a valid election period

A solid understanding of enrollment periods ensures agents can provide accurate guidance and avoid common pitfalls that may affect a client’s coverage. If additional clarification is needed, agents should refer to carrier policy materials, CMS guidelines, or reach out to the Broker Support Team for assistance. Keeping these rules top of mind helps ensure a smooth, compliant enrollment experience for every client.