Medicare Supplement, also known as Medigap, is supplemental insurance that fills in the gaps of Original Medicare. If you have decided that a Medigap policy is the right insurance for you, then you will want to sign up when you’re first eligible.

What is the Medigap Initial Enrollment Period?

Medigap’s initial enrollment is a one-time 6-month application time period that guarantees that you will be approved for a Medigap. If you miss the initial enrollment window you will usually have to answer health questions and could be denied coverage.

When is the Medigap Initial Enrollment Period?

Medigap initial enrollment usually starts the first of the month when you turn 65*, and runs for six months. You can, however, apply up to three months before your 65th birthday so that your Medigap start date will match your Medicare Part B start date. The same happens if you live in a state where you are under 65 but able to get Medigap.

If you chose to delay your Medicare Part B enrollment because you have creditable coverage (usually job-based insurance), the 6 month initial enrollment period begins on your Part B effective date. Try our Medicare deadline calculator to help you figure out when to apply for Medicare health plans.

When you sign up for Medigap*: When your Medigap effective will begin:
3 months before your 65th birth month The 1st of your 65th birth month
During your birth month The 1st of the following month
During your 65th birth month The 1st of the following month
During the 5 months after your 65th birth month The 1st of the following month

*This whole chart assumes your Part B effective date is active

Learn More about Medigap Get a Medigap Quote

What if you Miss the Medigap Initial Enrollment Period?

If you miss your initial enrollment period you’ll usually have to go through medical underwriting unless you live in CT and NY or you qualify for a few special enrollment. Medical underwriting just means you’ll have to answer medical questions before you will be approved. If you have certain preexisting conditions, you could be denied or charged more. Don’t give up hope! There are some companies that are easier to get approved from than others. We at consider ourselves the Medigap enrollment experts. We can help you choose a company that will work best for your health and financial needs, call our licensed independent insurance agents at 800-930-7956.


  • If you were eligible for Part B early due to a disability, you will have a new initial enrollment period when you turn 65.
  • If your birthday falls on the first of the month both your Medicare part B and Medigap plan can start the first of the month preceding your 65th birthday
  • If you chose not to delay Medicare Part B, but have creditable coverage, when you leave that coverage you will have 63 days to enroll in a handful of Medigap plans