Updated March 2026
Medicare is the federal program that pays for medical services provided to individuals who have reached the age of 65. Medicare only covers eligible services, which are typically those provided or ordered by a doctor to help a patient recover from an injury or illness. Medicare does not pay for services that are not medically necessary or for services that help patients manage a long-term condition from which recovery is not expected.
Even if a service is covered by Medicare, the patient may be required to pay part of the cost. Some seniors insure themselves against the portion of a bill that Medicare does not pay by purchasing “Medigap” coverage.
Tip: For basic information about Medicare, how it works, and what it covers, see Medicare: Learn About Medicare Basics. For important information about what Medicare does not cover, see What’s Not Covered?
What is Medigap?
Medigap is the informal name given to Medicare Supplement Insurance policies. The policies are sold by private insurance companies. The policies pay for copayments, coinsurance, and deductibles that are not covered by Medicare.
As a general rule, a Medigap policy does not cover services unless Medicare pays its share of those services. In other words, if a service is not covered by Medicare, it will not be covered by a typical Medigap policy. Only the portion of a covered service that is not paid by Medicare is covered by Medigap insurance.
Some policies make an exception for certain expenses that Medicare does not cover, such as medical care that you receive when you travel outside the United States. Those exceptions are usually quite limited. You should not expect a Medigap policy to pay for dental care, eye care or eyeglasses, long-term assisted living care, or other services that Medicare does not cover.
Does Medigap pay for prescription drugs?
Medigap does not pay for prescription drugs (some Medigap policies sold before January 2006 had limited prescription drug coverage, but they are no longer available). You can also obtain prescription drug coverage through a Medicare Advantage plan (Part C). You can get prescription drug coverage by joining a Medicare Prescription Drug Plan (Medicare Part D).
Who is eligible for Medigap?
If you are eligible for Medicare, you will probably be able to buy Medigap coverage. However, you must have both Medicare Part A and Medicare Part B as a condition of obtaining Medigap insurance.
You can buy Medigap coverage at any point after you turn 65 and purchase coverage under Medicare Parts A and B. However, you benefit from enrolling in Medigap during the 6-month Medigap Open Enrollment period that begins when you enroll in Medicare Part B. During that one-time 6-month window, an insurer cannot deny you coverage or charge you more due to pre-existing health conditions. If you let the six months expire without purchasing a Medigap policy, insurers can charge you more if you have a preexisting condition, can exclude the preexisting condition from coverage, or can deny you coverage entirely.
If you have a Medicare Medical Savings Account (MSA) Plan, you cannot buy Medigap coverage. If you have a Medicare Advantage Plan, you can buy Medigap coverage, but to avoid duplicating your coverage you should leave the Medicare Advantage Plan before you purchase Medigap coverage.
Can my insurer drop my Medigap coverage?
If you enroll during the Medigap Open Enrollment Period discussed above, renewal of your Medigap coverage is guaranteed for as long as you continue to pay your premiums. Regardless of when you enroll, once a Medigap policy is issued, the insurer cannot cancel your coverage because of your health condition, provided your premium payments are current.
How can I learn more about Medigap?
The United States government has helpful information online if you want to explore Medigap coverage in more detail. You might want to visit the following pages:
(This article was reviewed March, 2026.)