Medicare Supplement Insurance Explained
Medigap Made Simple
Medicare Supplement Insurance, also called Medigap, is extra insurance you can buy from a private insurance company to help pay some of your share of out-of-pocket costs in Original Medicare, such as copayments, coinsurance, and deductibles.
Medigap is called “supplement” insurance because it works alongside Original Medicare. It does not replace Medicare. It helps fill certain cost gaps that may be left after Medicare Part A and Part B pay their share.
Our goal is to help you understand what Medigap is, how it works, what it may help cover, what it does not cover, when you can buy a policy, and how it fits with the rest of Medicare.
This page is educational only. We do not recommend any specific Medigap plan, insurance company, premium, or coverage choice.
What Is Medigap?
Medigap is private insurance designed to work with Original Medicare.
Original Medicare includes Medicare Part A and Medicare Part B. Part A helps cover hospital insurance, and Part B helps cover medical insurance. Medigap can help pay some of the out-of-pocket costs you may owe after Original Medicare pays its share.
A simple way to remember it:
Medigap helps cover some of the “gaps” in Original Medicare costs.
These gaps may include certain deductibles, copayments, and coinsurance. Medigap does not pay for everything, and it is not the same as Medicare Advantage.
Why Is It Called Medigap?
The name Medigap comes from the idea that the policy helps fill some of the cost gaps in Original Medicare.
Original Medicare may pay a large portion of covered healthcare costs, but you may still be responsible for certain out-of-pocket costs. Medigap policies are designed to help with some of those costs, depending on the type of policy you choose.
That is why you may see both names used:
Medicare Supplement Insurance
Medigap
Medigap policy
Medicare Supplement policy
They generally refer to the same type of coverage.
How Does Medigap Work?
Medigap works together with Original Medicare.
When you receive Medicare-covered care, Medicare generally pays its share of the Medicare-approved amount first. Then your Medigap policy may pay part or all of the remaining amount you owe, depending on your policy. Medicare.gov explains that, with most Medigap policies, the insurance company receives your Part B claim information directly from Medicare and then pays the amount owed under your policy.
A simple way to think about it:
Original Medicare pays first.Medigap may help pay some remaining approved costs.You pay anything left over.
Medigap does not change what Medicare covers. It helps with certain costs after Original Medicare pays.
You Must Have Original Medicare to Buy Medigap
In most cases, you must have Original Medicare, meaning both Medicare Part A and Medicare Part B, before you can buy a Medigap policy. Medicare.gov explains that you can only buy Medigap if you have Original Medicare, which generally means you must sign up for Part A and Part B first.
This is one of the most important rules to understand:
Medigap works with Original Medicare.
It is not designed to work with Medicare Advantage, and it cannot be used to pay Medicare Advantage plan copayments, deductibles, or premiums.
What Does Medigap Help Cover?
Medigap policies help cover your share of costs for services that are covered by Original Medicare. These may include costs such as copayments, coinsurance, and deductibles.
Depending on the policy, Medigap may help with costs related to:
Part A hospital coinsurance
Part B coinsurance or copayments
Blood costs
Part A hospice care coinsurance or copayments
Skilled nursing facility care coinsurance
Part A deductible
Certain other Original Medicare cost-sharing amounts
Some Medigap policies may also cover certain services Original Medicare does not cover, such as emergency medical care during foreign travel, subject to plan limits.
This page is not comparing specific Medigap plan letters. The goal here is to help you understand what Medigap is and how it fits into the bigger Medicare picture.
What Medigap Does Not Cover
Medigap does not cover everything.
Medigap policies generally do not cover long-term care, routine vision or dental care, hearing aids, eyeglasses, or private-duty nursing.
Medigap also does not usually include prescription drug coverage. Medigap policies sold after 2005 do not include prescription drug coverage. If you want prescription drug coverage, you can enroll in a separate Medicare Part D drug plan.
A simple way to remember it:
Medigap helps with some Original Medicare costs. It is not a full replacement for every type of healthcare coverage you may need.
Medigap and Prescription Drug Coverage
Medigap is not the same as Medicare Part D.
Medicare Part D helps cover prescription drugs. Medigap helps with certain Original Medicare out-of-pocket costs. These are different types of coverage. Medigap policies sold after 2005 do not include prescription drug coverage, so people who want drug coverage can join a separate Medicare drug plan.
A simple way to think about it:
Original Medicare = Part A + Part BMedigap = helps with some Original Medicare out-of-pocket costsPart D = helps with prescription drugs
If you choose Original Medicare, you may consider both Medigap and Part D, depending on your needs.
Medigap Is Different From Medicare Advantage
Medigap and Medicare Advantage are often confused, but they are not the same.
Medigap is a supplement to Original Medicare. It works with Medicare Part A and Part B to help pay some of your share of covered costs.
Medicare Advantage, also called Part C, is another way to receive your Medicare coverage through a private insurance company approved by Medicare.
When you are getting started with Medicare, you can either buy Medigap or enroll in a Medicare Advantage plan, but you cannot have both.
A simple way to remember it:
Medigap works with Original Medicare. Medicare Advantage is an alternative to Original Medicare.
That does not mean one is automatically better than the other. It means they work differently.
Can You Have Medigap and Medicare Advantage at the Same Time?
No.
You cannot buy Medigap while you are in a Medicare Advantage plan unless you are switching back to Original Medicare. You also cannot use Medigap to pay Medicare Advantage copayments, deductibles, or premiums.
This is one of the biggest Medicare misunderstandings.
If you are comparing Medicare coverage options, it is helpful to think of the two common paths this way:
Path 1:
Original Medicare + optional Medigap + optional Part D
Path 2:
Medicare AdvantageThis is not a recommendation. It is simply the basic structure.
Medigap Policies Are Standardized
In most states, Medigap policies are standardized and identified by letters. Policies with the same letter offer the same basic benefits no matter where you live or which insurance company sells the policy. In most states, there are 10 different types of Medigap plans named by letters: A through D, F, G, and K through N.
This is important because it means a policy with the same letter has the same basic benefits, even if sold by different insurance companies.
However, the price can vary.
The benefits in each lettered plan are the same no matter which insurance company sells it, and that the price is the only difference between policies with the same plan letter sold by different companies.
A simple way to remember it:
Same letter = same basic benefits. Price and company can vary.
Massachusetts, Minnesota, and Wisconsin standardize Medigap policies differently.
Why Medigap Prices Can Vary
Medigap premiums can vary widely depending on the insurance company, the plan, and where you live. Each insurance company decides how it sets the premium for its Medigap policies, which can affect what you pay now and in the future.
Your Medigap cost may also depend on factors such as:
Where you live
Which insurance company sells the policy
Which standardized policy type you choose
Whether the company offers discounts
Whether medical underwriting applies
Whether you have a guaranteed issue right
Whether the policy is a Medicare SELECT policy
Whether a high-deductible option is available
Medicare.gov also explains that when you buy a Medigap policy, you pay a monthly premium to the private insurance company, and you also must continue paying your monthly Medicare Part B premium. Medicare does not pay the premium for your Medigap policy.
Medigap Covers One Person
A Medigap policy covers only one person.
If you and your spouse both want Medigap coverage, each of you would need to buy your own policy. Medicare.gov explains that a Medigap policy only covers one person, so spouses must each buy their own policy if both want coverage.
This is different from some employer or family health plans that may cover more than one person under the same policy.
When Can You Buy a Medigap Policy?
The best time for many people to buy a Medigap policy is during their Medigap Open Enrollment Period.
Under federal law, this is a six-month period that begins the first month you have Medicare Part B and are age 65 or older. During this time, you can enroll in any Medigap policy sold in your state, and the insurance company cannot deny you coverage because of pre-existing health problems.
This is a one-time enrollment period. It does not repeat every year like the Medicare Open Enrollment Period.
A simple way to remember it:
Your Medigap Open Enrollment Period starts when you are 65 or older and enrolled in Part B. It lasts six months.
What Happens If You Miss Your Medigap Open Enrollment Period?
If you miss your Medigap Open Enrollment Period, your options may be more limited.
Medicare.gov explains that outside of your Medigap Open Enrollment Period, you may have to pay more for a policy, fewer options may be available, and an insurance company may be allowed to deny you a policy if you do not meet its medical underwriting requirements.
That is why timing matters.
Unlike Medicare Advantage or Part D, Medigap does not have a simple annual shopping window where everyone automatically gets the same federal right to buy any policy without medical underwriting.
Some people may have special protections, known as guaranteed issue rights.
What Are Guaranteed Issue Rights?
Guaranteed issue rights are protections that may allow you to buy certain Medigap policies in specific situations.
Medicare.gov explains that guaranteed issue rights, also called Medigap protections, are situations where an insurance company cannot deny you a Medigap policy. These protections may apply in certain situations outside your Medigap Open Enrollment Period.
Examples may include certain situations where you lose other coverage or switch back to Original Medicare.
Because guaranteed issue rights can depend on your situation and state rules, it is important to keep letters, notices, emails, or claim denials that show your coverage changed or ended. Medicare.gov notes that you may need documents like these to prove you have the right to buy a Medigap policy.
What Is Medical Underwriting?
Medical underwriting is when an insurance company reviews your health history before deciding whether to sell you a policy, what policy options are available, or what price you may pay.
During your Medigap Open Enrollment Period, insurance companies cannot use medical underwriting to deny you coverage or charge you more because of pre-existing health problems.
Outside that window, medical underwriting may apply unless you have a guaranteed issue right or another protection under state law.
This is one reason Medigap timing is so important.
Can You Change Medigap Policies Later?
Sometimes, but it is not always simple.
Medicare.gov explains that, in most cases, you will not have a federal right to switch Medigap policies unless you are within your six-month Medigap Open Enrollment Period or you are eligible under a specific situation or guaranteed issue right.
If you are able to switch, you may also have a 30-day “free look” period after buying a new Medigap policy. Medicare.gov explains that during this period, you can decide whether to keep the new policy, but you should not cancel your old policy until you decide to keep the new one, and you may need to pay both premiums during that month.
The main takeaway:
Changing Medigap later may be possible, but it is not always guaranteed.
What If You Are Under 65?
If you have Medicare before age 65 because of a disability or End-Stage Renal Disease, your Medigap options may depend on your state.
Medicare.gov explains that federal law generally does not require insurance companies to sell Medigap policies to people under 65, although some states do offer Medigap rights to people under 65. You should check with your State Insurance Department about rights under state law.
This is an important area where rules can vary by state.
Medigap and Medicare SELECT
In some states, you may be able to buy a type of Medigap policy called Medicare SELECT.
Medicare.gov explains that Medicare SELECT policies may require you to use certain providers, and the premium may be lower. In some cases, if you buy a Medicare SELECT policy, you have the right to change your mind within 12 months and switch to a standard Medigap policy.
This is not available the same way everywhere, so it is another reason to review options based on your state and county.
What to Ask Before Buying a Medigap Policy
Because Medigap policies are standardized in most states, comparing them is different from comparing some other types of insurance.
Before buying a Medigap policy, consider asking:
Do I have Original Medicare Part A and Part B?
Am I in my Medigap Open Enrollment Period?
Do I have a guaranteed issue right?
Which standardized Medigap policy types are sold in my state?
Does this company offer the policy type I am considering?
What is the monthly premium?
How does the company set future premiums?
Are discounts available?
Does medical underwriting apply?
Is this a standard Medigap policy or Medicare SELECT?
Do I also need separate Part D prescription drug coverage?
How does this fit with my doctors, budget, and healthcare needs?
The key is not simply choosing a name you recognize. It is understanding how Medigap fits with Original Medicare and what your responsibilities may be.
Common Misunderstandings About Medigap
“Medigap is the same as Medicare Advantage.”
No. Medigap supplements Original Medicare. Medicare Advantage is another way to receive your Medicare coverage. Medicare.gov explains that you can either buy Medigap or enroll in Medicare Advantage, but you cannot have both.
“Medigap replaces Medicare.”
No. Medigap does not replace Medicare. You must have Original Medicare to buy a Medigap policy. Medicare pays its share first, and then Medigap may help pay some remaining costs, depending on your policy.
“Medigap includes prescription drug coverage.”
Generally, no. Medigap policies sold after 2005 do not include prescription drug coverage. If you want prescription drug coverage, you can join a separate Medicare Part D drug plan.
“I can buy Medigap anytime with no questions asked.”
Not always. Your six-month Medigap Open Enrollment Period is usually the best time to buy. After that, you may have fewer options, may pay more, or may be denied based on underwriting unless you have certain protections.
“My spouse and I can share one Medigap policy.”
No. A Medigap policy covers only one person. If both spouses want Medigap coverage, each person needs a separate policy.
Common Questions About Medigap
What is Medicare Supplement Insurance?
Medicare Supplement Insurance, or Medigap, is extra insurance sold by private insurance companies to help pay some out-of-pocket costs in Original Medicare, such as copayments, coinsurance, and deductibles.
Do I need Original Medicare to buy Medigap?
Yes. In most cases, you must have Medicare Part A and Part B before you can buy a Medigap policy.
Can I have Medigap with Medicare Advantage?
No. Medicare.gov explains that you can either buy Medigap or enroll in a Medicare Advantage plan, but you cannot have both. You also cannot use Medigap to pay Medicare Advantage copayments, deductibles, or premiums.
Does Medigap cover prescription drugs?
Medigap policies sold after 2005 do not include prescription drug coverage. If you want drug coverage, you can enroll in a separate Medicare Part D plan.
Is Medigap the same in every state?
In most states, Medigap policies are standardized by letter. Policies with the same letter offer the same basic benefits regardless of insurance company. Massachusetts, Minnesota, and Wisconsin standardize Medigap policies differently.
Why do Medigap premiums differ if benefits are standardized?
Medigap premiums can vary by insurance company, plan type, and location. Medicare.gov explains that even when the benefits are the same for the same lettered plan, premiums can vary significantly between companies.
When is the best time to buy Medigap?
For many people, the best time is during the six-month Medigap Open Enrollment Period. This begins the first month you have Part B and are age 65 or older. During this time, insurance companies cannot deny you coverage because of pre-existing health problems.
The Simple Takeaway
Medicare Supplement Insurance, also called Medigap, helps pay some of your share of out-of-pocket costs in Original Medicare.
It works with Original Medicare, not Medicare Advantage. It does not usually include prescription drug coverage. In most states, policies are standardized by letter, but premiums can vary by insurance company and location.
The most important things to understand are:
Medigap works with Original Medicare.
You generally need Part A and Part B to buy it.
It may help pay certain Original Medicare out-of-pocket costs.
It does not replace Medicare.
It is different from Medicare Advantage.
Timing matters because your Medigap Open Enrollment Period does not repeat every year.
Understanding Medigap helps you better understand one of the main coverage paths available after you enroll in Medicare.
Need Help Understanding Medigap?
Medigap can be confusing because timing, premiums, underwriting, state rules, and prescription drug coverage all matter.
If you are trying to understand how Medigap works with Original Medicare, Part D, or Medicare Advantage, we can help connect you with a licensed Medicare professional who can answer questions based on your situation.