Medicare Supplement (Medigap)
Medigap can make Original Medicare costs more predictable, but enrollment timing and long-term pricing matter.
What Medigap does
Medigap is private supplemental insurance designed to help pay specified out-of-pocket costs in Original Medicare. It does not replace Original Medicare. Medicare remains primary and the Medigap policy supplements it.
Standardized benefits make comparison different
In most states, Medigap plans are standardized by letter. That means one carrier’s Plan G covers the same standardized benefits as another carrier’s Plan G. Premium, pricing history, household discounts, service and underwriting practices can still differ.
The enrollment window deserves attention
Your federal Medigap Open Enrollment Period lasts six months and begins the first month you are 65 or older and enrolled in Part B. During that period, you can buy a Medigap policy sold in your state even if you have health problems.
After that window, an insurer may be allowed to deny an application or charge differently based on underwriting unless you have a guaranteed-issue right or stronger state protection.
Plan G and Plan N are not interchangeable
Both are commonly considered by new Medicare beneficiaries, but they handle Part B cost-sharing differently. See the dedicated Plan G vs. Plan N comparison.
Frequently asked questions
When is Medigap Open Enrollment?
It lasts six months and starts the first month you are 65 or older and enrolled in Medicare Part B.
Are benefits standardized?
In most states, lettered Medigap plans are standardized, so the core benefits for the same plan letter are the same regardless of insurer.
Can I buy Medigap any time without underwriting?
Not necessarily. Outside your Medigap Open Enrollment Period or a guaranteed-issue situation, an insurer may be allowed to use medical underwriting, subject to state law.
Primary sources
This guide is based on current information from Medicare.gov and CMS. Rules can change, so verify time-sensitive details before acting.