Medicare Supplement Insurance

Medicare supplement insurance (Medigap) helps pay some of the out-of-pocket health care costs that Original Medicare (Parts A and B) doesn’t pay. It isn’t a government benefit, like Parts A and B. Plans are offered through private insurance companies. It’s your decision whether to buy a plan or not.

What Does Medicare Supplement Insurance Cover?

A Medicare supplement plan (also known as a Gap plan) is to cover some of the out-of-pocket costs not paid by Medicare Parts A and B, like deductibles, copays and coinsurance. Each of the standardized plans provides benefits for different out-of-pocket costs.

Each standardized plan with the same letter must offer the same basic benefits, no matter which insurance company sells it. For example the basic benefits of one company’s Plan F are the same as the basic benefits of another company’s Plan F. The only difference between Medicare supplement plans with the same letter sold by different insurance companies is the premium.

What Does Medicare Supplement Insurance Cost?

This shows costs you may have with a Medicare supplement insurance plan. You need to look at individual plans to understand their specific costs.


Plan premiums can vary from company to company, even for exactly the same coverage. You continue to pay the Part B premium to Medicare as well.


You may pay Part A and Part B deductibles with some Medicare supplement plans. The high-deductible Plan F has an annual plan deductible.


You may pay a set co-payment for covered Part B services with some Medicare supplement plans. Co-insurance You may pay part of the co-insurance amount for covered Part B services with some Medicare supplement plans.

How Medicare Supplement Insurance Works

Each standardized Medicare supplement insurance plan covers different types of out-of-pocket costs. So what you pay in out-of-pocket costs will depend on what services you use and which plan you have.

Depending on which Medicare supplement insurance plan the person has some or all of their out-of-pocket costs could be covered. In general, plans that cover more costs have higher premiums.

Enrolling in a Medicare Supplement Insurance Plan

You have a specific enrollment period for Medicare supplement insurance called Medicare Supplement Open Enrollment Period. This period:

  1. Begins the first month that you are age 65 or older and enrolled in Medicare Part B
  2. Lasts for 6 months
  3. Guarantees your right to buy a plan (You cannot be denied coverage if you apply during this period.)

Even if you miss your open enrollment period, you may apply for Medicare supplement insurance at any time. You could be denied coverage, or charged a higher premium based on your health history. Some states have additional Medicare supplement open enrollment periods, including for beneficiaries under age 65.