Medicare Supplement Insurance, or Medigap, is health insurance that helps pay for costs that aren’t covered by Original Medicare, like certain copayments, coinsurance or deductibles.

Medicare Supplement Insurance operates as additional — not primary — insurance coverage. You must have Medicare Part A and Part B to buy a Medigap plan. The plans differ in terms of what they cover, out-of-pocket limits and premiums.

These policies are sold by private health insurance companies, and the plans are standardized, so Medigap Plan G from one company in New York will offer the same coverage as Medigap Plan G from a different company in Ohio
[1]
.

What you should know about Medicare Supplement Insurance plans
Here are the basics of how Medicare Supplement Insurance works
[2]
:

Medigap plans cover one person. If your spouse or partner also wants a Medicare Supplement Plan, they must buy a policy of their own.

Companies can’t cancel Medigap plans for health issues. All standardized Medigap plans are guaranteed renewable, which means health insurance companies can't cancel your policy if you have health problems, as long as you continue to pay the premiums.

Medigap doesn’t cover prescription drugs. Medigap policies are no longer allowed to include prescription drug coverage. For that, you’ll need a Medicare Part D Prescription Drug Plan.

You can’t buy Medigap if you have Medicare Advantage. In fact, it’s illegal for someone to sell you a Medigap plan if you have Medicare Advantage. If you change back to Original Medicare, you can purchase a Medigap plan, but you might be denied coverage or face higher prices if you sign up after your Medigap open enrollment period.

They don’t cover everything. Generally, Medicare Supplement Insurance doesn’t cover dental care, vision care, hearing aids, long-term care, eyeglasses or private-duty nursing.

Some plans are no longer available. You can no longer purchase Plans E, H, I and J, but if you purchased one of those plans before June 1, 2010, you can continue with it. People newly eligible for Medicare after Jan. 1, 2020, also can’t purchase Plan C and Plan F, which cover the Medicare Part B deductible. (But if you turned 65 prior to that date and haven't signed up for Medicare Part B because you still have employer group coverage, you may be able to buy Plans C and F when you do enroll in Part B.)

Types of Medicare Supplement Insurance plans
If you’re considering a Medigap policy, it helps to understand what each plan covers. There are 10 standardized Medigap plans available in most states, and they differ in terms of coverage for services, out-of-pocket limits and premium costs. (Massachusetts, Minnesota and Wisconsin use different standards.)

The best plan for you depends on where you live, your health and potential health care needs, your financial situation and your tolerance for risk. This table breaks down the 10 standard Medigap plan types into categories so you can learn more about which plans might be the best fit for you:

Get details on Medicare Supplement Insurance options

Coverage

Medigap Plan

Basic benefits

Medigap Plan A.

Basics plus some extras

Medigap Plan B.

Medigap Plan M.

Highest coverage

Medigap Plan D.

Medigap Plan G.

Lower premiums, but higher copays

Medigap Plan N.

Lowest premiums — partial coverage

Medigap Plan K.

Medigap Plan L.

No longer for sale to new Medicare members

Medigap Plan C.

Medigap Plan F.

Medicare Supplement Insurance plan comparison chart
Here’s a Medicare Supplement Insurance plan comparison chart to help you see what's covered by each plan type, according to Medicare.gov
[3]
:

Medigap benefit

Medigap plans that cover it

Part A coinsurance and hospital costs up to an additional 365 days after Medicare benefits are used up.

A, B, C, D, F*, G*, K, L, M, N.

Part B coinsurance or copayment.

A, B, C, D, F*, G*, M, N**.

K covers 50%.

L covers 75%.

Blood (first 3 pints).

A, B, C, D, F*, G*, M, N.

K covers 50%.

L covers 75%.

Part A hospice care coinsurance or copayment.

A, B, C, D, F*, G*, M, N.

K covers 50%.

L covers 75%.

Skilled nursing facility care coinsurance.

C, D, F*, G*, M, N.

K covers 50%.

L covers 75%.

Part A deductible.

B, C, D, F*, G*, N.

K and M cover 50%.

L covers 75%.

Part B deductible.

C, F*.

Part B excess charge.

F*, G*.

Foreign travel exchange (deductible and limitations apply).

C, D, F*, G*, M and N** cover at 80%.

Out-of-pocket limit***.

K: $6,940 in 2023.

L: $3,470 in 2023.

N/A for all other plans.

* In some states, Plans F and G have a high-deductible plan option. That means you must pay for Medicare-covered costs (coinsurance, copayments, deductibles) up to the deductible of $2,700 in 2023, at which point your coverage will kick in.

** Plan N pays 100% of the Part B coinsurance, except for a copayment of up to $20 for some office visits and a copayment of up to $50 for emergency room visits that don’t lead to inpatient admission.

*** For Plans K and L, once you meet your out-of-pocket yearly limit and your yearly Part B deductible, the plan pays 100% of covered services for the remainder of the year.

Find Medicare Supplement Insurance near you
You can search for Medicare Supplement Insurance in your area on Medicare.gov. Just enter your ZIP code, and for more accurate pricing, consider entering your age, sex and tobacco usage on the page that follows.

Once you pick your Medigap plan, the finder will show you companies in your area that offer it.

» MORE: Best Medicare Supplement Insurance companies
Looking for Unbiased Medicare Advice?
Chapter saves people over $1,000/year on their Medicare plans. You can reach them at (855)480-7438
Chapter (mobile image)
When to enroll in Medicare Supplement Insurance
Ideally, you should buy Medicare Supplement Insurance during your Medigap Open Enrollment Period
[4]
.

This period happens only once. It starts once you’re 65 and enrolled in Medicare Part B, and lasts for six months. (If you're still working after 65 and covered by a group employer plan that is deemed creditable coverage, your six-month period starts after you’ve ended active employment or no longer have that insurance.)

Medigap policies are cheapest and easiest to get during this open enrollment period because insurance companies aren’t allowed to factor your health or medical history into your price. After the period ends, the prices may go up or you may be denied coverage due to your health status or medical history.

In some states, insurance companies sell Medigap plans to those under 65 who are living with a disability and are eligible for Medicare. You can find more information through your State Health Insurance Assistance Program, or SHIP.

If you have additional questions about Medicare, visit Medicare.gov or call 800-MEDICARE (800-633-4227, TTY 877-486-2048).