Medicare offers several enrollment times, including special enrollment periods, during which a person can enroll in or change health insurance coverage.

This article discusses Medicare enrollment periods, including the special enrollment period (SEP). It also looks at what can be done during an SEP, when the changes can be made, and SEP coverage and costs.

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Medicare is a federal program with four parts:

  • Part A, which is hospital insurance
  • Part B, which is medical insurance
  • Part C, also known as Medicare Advantage
  • Part D, which is prescription drug coverage

There are three Medicare enrollment periods as outlined below. There is also a SEP, which is shown in more detail in the next section.

Initial enrollment period

A person’s initial enrollment period (IEP) starts 3 months before the month a person turns 65, includes their birthday month, and extends to the following 3 months.

Some people are automatically enrolled in original Medicare (Part A and Part B), including anyone who gets Social Security or Railroad Retirement Board benefits. If a person is not automatically enrolled, they can do so online or at their local Social Security office.

During their IEP, a person can also enroll in a Medicare Part D prescription drug plan, or in Part C, Medicare Advantage.

Late penalty

A person may incur a late penalty if they wait to enroll after their IEP.

General enrollment period

The Medicare general enrollment period (GEP) is between January 1–March 31 every year. It is also called the Advantage open enrollment period.

During the GEP, a person can make only one change, which may be to enroll in original Medicare, switch Medicare Advantage plans, or leave a Medicare Advantage plan to enroll in original Medicare.

Enrollment during the GEP means coverage generally starts on July 1.

Late penalty

A person who enrolls in Medicare parts A and B during the GEP may pay a late penalty on the premium.

Open enrollment period

The period from October 15–December 7 is the open enrollment period OEP), and is sometimes called the annual enrollment period.

During this time, a person can switch between Medicare Advantage plans, change from original Medicare to an Advantage plan or vice versa, and can also enroll or leave a Medicare Part D prescription drug plan.

A person can use this online tool to compare plans.

Any changes a person makes usually takes effect January of the following year.

During the Medicare SEPs, a person can enroll in or make changes to their Medicare plans, including original Medicare Part A and Part B, Medicare Advantage plans, or Medicare Part D prescription drug plans.


Eligibility for a SEP depends on various circumstances, such as:

  • a person’s employer group healthcare plan ends, or a person is enrolled in an alternative health plan
  • employment ends
  • a person no longer qualifies for Medicaid
  • a person moves to a new location, or returns to the United States from abroad
  • a person is released from prison
  • the plan changes its contract
  • a person is offered other coverage

There are also several other circumstances when a person may be eligible for a SEP, such as being eligible for both Medicare and Medicaid, or qualifying for Extra Help.

This online tool can help a person find out if they qualify for a SEP.

When can I make changes?

Each SEP has different and separate rules regarding when a person can make changes or enroll in a new plan. For example:

In general, there is a 3 month time period to make changes if a person moves to a new location or returns to the U.S. from abroad. A person can change plans 1 month before they move, during the month they move, and for the following month, as long as they inform the plan before they move. If a person waits until after they move, they can make changes in that month, plus the following 2 months.

If a person is offered other coverage by their employer, this change can be made as soon as the employer allows a person to enroll in the private plan. A person can then drop their current prescription drug plan or their Medicare Advantage plan.

The federal assistance program called Extra Help is designed to help people with limited income and resources pay the costs of Medicare prescription drugs.

If a person is eligible for Extra Help, there are SEPs that cover these circumstances.

  • If a person is eligible for both Medicaid and Medicare, they can switch, enroll in, or drop a Medicare prescription drug plan or a Medicare Advantage plan.
  • If a person gets Extra Help to pay for Medicare prescription drug coverage, they can enroll in, drop, or switch a Medicare prescription drug plan.
  • If a person is enrolled in a state pharmaceutical assistance program (SPAP) or lose SPAP eligibility, they can enroll in a Medicare Advantage plan with prescription drug coverage, or enroll in a Medicare prescription drug plan.

When can I make the changes?

Generally, a person eligible for Extra Help can make one change during each of these time periods:

  • January–March
  • April–June
  • July–September

However, a person who loses SPAP eligibility, or is enrolled in a SPAP can make changes only once per calendar year.

When a person enrolls in an Advantage plan or Medicare parts B or D during a SEP, they do not pay a late enrollment penalty. However, a person who enrolls outside the SEP periods may have to pay a penalty on the premium for as long as they have Medicare.

Each Medicare SEP has different rules about when a person can make changes to or enroll in a new plan. Plans may include original Medicare Part A and B, a Medicare Advantage plan, or a Medicare Part D prescription drug plan.