Some insurance including Medicare Parts A and B (Original Medicare) may cover health insurance costs, but they don’t always pay for all of it. Enter the Medicare Supplement Insurance policy, also called Medigap.

It is a supplement insurance plan from a private insurer to help cover whatever the Original Medicare doesn’t cover. Medigap may cover some out-of-pocket expenses, copayments, and deductibles. Depending on the private insurance you work with, some plans might cover services such as medical care for when you travel outside of the U.S.

You must have Medicare Part A and Part B before buying your Medicare Supplement or Medigap policy. Once purchased they guarantee coverage for life, regardless of health or age as long as the premium is paid.

When you have both Original Medicare and Medigap, this is how the process works:

• First, Medicare pays a Medicare-approved amount for covered health care costs.
• Second, Medicare Supplement/Medigap policy pays its share.

A Medigap policy is different from a Medicare Advantage Plan. If you already have a Medicare Advantage Plan, you cannot buy a Medigap policy. In fact, it is illegal to sell Medigap policies to people with a Medicare Advantage Plan.

The Medigap policies job is to supplement the Original Medicare policy. You can buy a Medicare Supplement/Medigap policy from any insurance company or insurance agent that has a license in your state to sell the policy.

All Medigap policies have a basic benefit structure as set by the Federal government. This means they all have the same basic features. However, some may offer additional benefits. You should always consult your insurance agent and compare policies.

Medical Supplement Insurance doesn’t cover everything. It generally doesn’t include vision, dental, eyeglasses, hearing aids, long-term care, or private duty nursing. Medigap policies do not include prescription drug coverage. That requires subscribing to a Medicare Prescription Drug Plan (Part D). Part D works with Original Medicare and Medigap.

When you purchase a Medicare Supplement/Medigap policy, you pay a monthly premium to the private insurance company. This is in addition to the monthly premium that you pay Medicare.

You’ll want to buy during the annual open enrollment period or you are eligible to buy the first day of the month in which you are 65 years old and enrolled in Medicare Part B. Many states will allow you to purchase your policy a few months prior to your birthday month. It is important to purchase during this time, as you cannot be declined due to pre-existing conditions.

If someone does not enroll in Part B when first eligible, it may require paying a late enrollment penalty.