Understanding Medicare enrollment periods is crucial for ensuring continuous coverage and avoiding penalties. Missing a key enrollment window can lead to gaps in coverage, higher premiums, or delays in accessing necessary healthcare services.

Initial Enrollment Period (IEP)

The IEP is your first chance to sign up for Medicare. It lasts 7 months: beginning 3 months before the month you turn 65, including your birthday month, and ending 3 months after. For example, if your birthday is in May, your IEP runs from February through August.

Parts A and B Enrollment

• Part A (Hospital Insurance): Automatic enrollment if you receive Social Security or Railroad Retirement Board benefits at least 4 months before turning 65. If not, you must sign up during your IEP.
• Part B (Medical Insurance): Enrollment is not automatic for everyone. You must sign up during your IEP (unless you have creditable coverage through an employer/union) to avoid late penalties.

Special Enrollment Period (SEP)

SEPs allow you to enroll in Medicare Part B (and sometimes Part A) outside the IEP or GEP if you meet certain conditions, such as:

• Losing employer-sponsored health coverage
• Moving outside your plan’s service area
• Experiencing a natural disaster
• Having a disability and returning to work

The length and rules of SEPs vary depending on the qualifying event.

General Enrollment Period (GEP)

If you miss your IEP and don’t qualify for an SEP, you can enroll in Part A and/or Part B from January 1 – March 31 each year. Coverage begins July 1 of the same year. Late enrollment penalties may apply for Part B if you didn’t have valid coverage.

Medicare Advantage Open Enrollment Period (MA OEP)

Runs from January 1 – March 31 each year. During this time, individuals in a Medicare Advantage Plan can:

• Switch to a different Medicare Advantage Plan
• Disenroll from Medicare Advantage and return to Original Medicare (Parts A & B)

If you return to Original Medicare during the MA OEP, you also get a SEP to join a Part D (prescription drug) plan.

Annual Enrollment Period (AEP)

Also known as the Open Enrollment Period, AEP runs from October 15 – December 7 annually. During AEP, you can:

• Switch from Original Medicare to Medicare Advantage
• Switch from Medicare Advantage back to Original Medicare
• Change Medicare Advantage Plans
• Join, switch, or drop a Part D prescription drug plan
• Change Medigap plans (note: Medigap has its own enrollment rules)

Changes made during AEP take effect on January 1 of the following year.