Is there a best time to enroll in a Medicare supplement plan?

Is there a best time to enroll in a Medicare supplement plan?

Enrollment for Medicare Supplement insurance (Medigap) takes place during three different periods: the initial enrollment period, general enrollment period, and special enrollment periods. The most advantageous time to enroll for most people is the initial enrollment period.

Initial Enrollment Period

The initial enrollment period for Medigap is six months beginning on the first day of the month prior to an individual's 65th birthday. In order to enroll for Medigap, you must first be enrolled in Medicare Part A and Part B. Enrolling during this initial period protects enrollees from the following:

  • Refusal by a private insurance company to sell any Medigap policy.
  • Establishing a waiting period for the policy to take effect.
  • Extra fees based on pre-existing conditions.


Enrolling during this initial period does not protect enrollees from the following:

  • Refusal to pay out-of-pocket costs based on pre-existing conditions.
  • Enforcing a six-month waiting period before covering out-of-pocket costs based on pre-existing conditions that were diagnosed or treated in the six months prior to Medigap activation.

General Open Enrollment Period

Individuals can still enroll in Medigap after the six-month initial enrollment period, but protections for those with pre-existing conditions lapse. Coverage can be denied, or the cost of the premium can be increased.

Creditable Coverage

If you are 65 and still working or if your spouse is still working, the health care benefits that you may be receiving through this employment is called creditable coverage. When this coverage comes to an end, individuals have an eight-month special enrollment period. During this window, they can enroll for Medicare Part B with a penalty-free premium

If an individual does not enroll in Medigap during the initial enrollment period but has creditable coverage without a gap of 63 days or more, the waiting period for pre-existing conditions will be reduced or eliminated.

State Protections for Pre-existing Conditions

Massachusetts, New York, and Connecticut -  Pre-existing conditions are never used to determine eligibility or premiums. 

California  - Enrollees have 30 days following a birthday to switch plans of similar value. Pre-existing conditions cannot be used to determine eligibility or premium during this window of time. 

Missouri - Enrollees have 30 days before a policy expiration date to switch plans of the same letter. Pre-existing conditions cannot be used to determine eligibility or premium during this window of time. 

Maine - Insurers who offer Medigap must offer at least one plan for at least one month each year that does not use pre-existing conditions to determine eligibility or premium.

Special Enrollment Periods

For certain circumstances special enrollment periods will apply. These circumstances include the following:

  • Moving out of a plan’s area of service.
  • Losing creditable coverage.
  • Losing a Medigap plan because it discontinues service in your area or they stop following Medicare rules.
  • Switching from Medicare Advantage to Original Medicare with Medigap. *
  • Switching from Original Medicare with Medigap to Medicare Advantage and back to Original Medicare with Medigap.**


*The first time an individual enrolls in Medicare Advantage, he or she can switch back to Original Medicare within the first 12 months.

**If the original Medigap plan is still available, you are limited to switching back to this plan.

**Protection because of pre-existing conditions is only good the first time an individual switches back to a Medigap plan and only if it is within 12 months of leaving the plan.

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Is there a best time to enroll in a Medicare supplement plan?