Medicare Enrollment Periods 2026

Overview: The Four Medicare Enrollment Periods

Medicare does not allow open enrollment year-round. Instead, the program uses defined enrollment windows to manage when you can sign up, switch, or drop coverage. Understanding which window applies to your situation — and the deadlines for each — is essential to avoiding coverage gaps and late enrollment penalties.

Initial Enrollment Period (IEP)

The Initial Enrollment Period is your first opportunity to enroll in Medicare. It is a 7-month window centered on your 65th birthday month. For people already receiving Social Security benefits, enrollment is automatic. For everyone else, you must actively sign up during this window to avoid late penalties.

The IEP applies to both Part A and Part B. You can also enroll in a Medicare Advantage plan or a standalone Part D drug plan during your IEP. For full details on IEP timing and coverage start dates, see our When Does Medicare Start guide.

Annual Enrollment Period (AEP): October 15 – December 7

The Annual Enrollment Period — sometimes called the Fall Open Enrollment — is the most well-known Medicare enrollment window. It runs each year from October 15 through December 7, with all changes taking effect on January 1 of the following year.

During AEP, any Medicare beneficiary can:

• Switch from Original Medicare to a Medicare Advantage plan
• Switch from Medicare Advantage back to Original Medicare
• Switch from one Medicare Advantage plan to another
• Join, switch, or drop a Part D prescription drug plan
• Switch from a Medicare Advantage plan with drug coverage to one without (or vice versa)

General Enrollment Period (GEP): January 1 – March 31

The General Enrollment Period is the fallback enrollment window for people who missed their Initial Enrollment Period and don't have a qualifying Special Enrollment Period. It runs from January 1 through March 31 each year, with coverage beginning April 1.

The GEP is specifically for enrolling in Part B (medical insurance). If you missed your IEP for Part A and you don't qualify for premium-free Part A, you can also enroll in Part A during GEP.

Important: enrolling through the GEP rather than the IEP typically means you'll face a late enrollment penalty unless you had a qualifying reason for the delay. The Part B penalty is 10% of the standard premium per 12-month period you were eligible but not enrolled.

Medicare Advantage Open Enrollment Period: January 1 – March 31

The Medicare Advantage Open Enrollment Period (OEP) runs concurrently with the GEP but serves a different population. If you are already enrolled in a Medicare Advantage plan as of January 1, you can use the MA OEP to:

• Switch to a different Medicare Advantage plan
• Disenroll from Medicare Advantage and return to Original Medicare (you can also pick up a Part D plan at this time)

You cannot use the MA OEP to switch from Original Medicare to a Medicare Advantage plan — that switch can only happen during AEP or through a qualifying SEP.

Special Enrollment Periods (SEPs)

Special Enrollment Periods allow you to make Medicare changes outside the standard windows when certain qualifying life events occur. Most SEPs last 60 days from the date of the triggering event.

Common SEP Triggers

• Loss of employer-sponsored group health coverage (job loss, retirement, reduced hours)
• Employer or union coverage ending
• Moving to a new address outside your current plan's service area
• Moving into or out of a nursing home or long-term care facility
• Becoming newly eligible for Medicaid or Extra Help (Low Income Subsidy)
• Losing Medicaid or Extra Help eligibility
• Your Medicare Advantage plan loses its Medicare contract or leaves your area
• You are released from incarceration
• You were enrolled in a plan based on fraudulent information from the plan
• You qualify for a Medicare Savings Program (QMB, SLMB, QI)
• You are Native American or Alaskan Native (may enroll at any time)
• You become eligible for both Medicare and Medicaid (dual eligible)

Late Enrollment Penalties

Missing your enrollment window without a qualifying reason can result in permanent premium increases:

Use our Part D Penalty Calculator to estimate your specific penalty amount based on how long you've been without coverage.