Learning Center > What is Medicare Supplement Insurance (Medigap)?

What is Medicare Supplement Insurance (Medigap)?

Original Medicare provides basic hospital and medical insurance coverage to Medicare enrollees. Depending on your healthcare needs, this could leave you with coverage gaps. But there are two primary ways to close them: through a Medicare Advantage plan or through Medicare Supplement Insurance (also known as Medigap).

In this Medicare Supplement guide, we’ll review all of the Medigap basics, including:

  • What is Medigap insurance?
  • What services and benefits are covered under Medicare Supplement?
  • Who is eligible for Medigap?
  • Medicare Supplement costs
  • When are the Medicare Supplement enrollment periods?
  • How does Medigap work with other insurance plans?
  • Medicare Supplement and special scenarios
  • What’s the difference between Medicare Advantage and Medicare Supplement?
  • Advantages and Disadvantages of Medigap plans

What is Medigap Insurance (Medicare Supplement)?

Medicare Supplement, also known as Medigap, is a category of Medicare insurance products offered by private insurance companies. Medigap plans are designed to work with Original Medicare, and they can close some, or all, of the gaps in your Original Medicare coverage. In other words, these plans are designed to reduce your out-of-pocket spending in Medicare.

Types of Medigap Insurance Plans

There are 10 standardized Medigap plans, each identified by letters: A, B, C, D, F, G, K, L, M, and N. There are also high-deductible versions of plans F and G. Each Medigap plan covers a different mix of your out-of-pocket costs under Original Medicare.

Medicare Supplement benefits are standardized across 47 states: Minnesota, Wisconsin, and Massachusetts have their own regulations. That said, this Medicare Supplement guide will focus on the 10 standardized Medigap plans. Below is a breakdown of what each Medigap plan covers.

Medigap Plan A

The most basic Medigap plan is Plan A, which covers your:

  • Part A coinsurance/copay for an additional 365 days in the hospital (beyond Original Medicare)
  • Part B coinsurance/copayments
  • First three pints of blood
  • Part A hospice care coinsurance/copay

Medigap Plan B

Plan B offers a little more coverage, including everything offered by Plan A, plus the Part A deductible.

Medigap Plan C

Plan C covers what Plans A and B do, plus the following:

  • Skilled nursing facility coinsurance/copayments
  • Part B deductible
  • Emergency foreign travel

Plan C is no longer available for people who became eligible for Medicare after 12/31/2019. But if you became eligible for Medicare before that date, Plan C remains available to you.

Medigap Plan D

Plan D covers everything covered by Plan C, except for the Part B deductible.

Medigap Plan F

Plan F is the most comprehensive Medicare Supplement Insurance plan available. It closes many gaps, covering everything Plan C covers, plus Part B excess charges.

But like Plan C, Plan F isn’t available to those who became eligible for Medicare after 12/31/2019.

Medigap Plan G

Plan G is the next-most comprehensive plan. Plan G covers all of the gaps except for the Part B deductible.

Medigap Plan K

Plan K has an unusual structure, covering 50% of many of the gaps. Plan K covers:

  • 100% of Part A coinsurance/copays for up to 365 additional hospital days
  • 50% of Part B coinsurance/copays
  • 50% of the cost of your first three pints of blood
  • 50% of Part A hospice care coinsurance/copays
  • 50% of Skilled Nursing Facility care coinsurance
  • 50% of the Part A deductible
  • Out-of-pocket maximum of $6,220 (2021 amount)
  • Plan K does not cover:
  • Part B deductible
  • Part B excess charges
  • Foreign travel

Medigap Plan L

Plan L covers 75% of a range of items (i.e. Part A deductible, Part B coinsurance, first three pints of blood, Part A hospice copayment, Part A skilled nursing coinsurance). Plan K, by comparison, covers those same items, but only at 50%. The out-of-pocket maximum for Plan L is $3,110 in 2021.

Medigap Plan M

Medigap Plan M covers everything that Plan D covers, except that Plan M only covers 50% of the Part A deductible.

Medigap Plan N

Medigap Plan N covers everything plan D does, with the exception of a copayment of up to $20 for Part B services and up to $50 for emergency room visits (this is waived if you’re admitted as an inpatient).

What Services Are Covered Under Medigap?

All of the services and procedures covered by Original Medicare are covered by Medicare Supplement, depending on which standardized plan you choose.

Original Medicare Part A

All Medicare-approved services and procedures covered by Medicare Part A are eligible, including:

  • Inpatient hospital stays
  • Skilled nursing care (non-custodial only)
  • Hospice care
  • Home health care

Original Medicare Part B

Medicare Supplement insurance can help pay for your share of costs under Medicare Part B, including:

Extra Benefits Provided By Medigap Plans

Some Medicare Supplement insurance plans offer additional benefits beyond what Original Medicare covers.

However, these benefits are not guaranteed and can change from year to year. Some of the most common extra Medigap benefits include:

  • Gym memberships and fitness programs like SilverSneakers
  • Discounts on vision, hearing, and prescription drugs
  • Access to nurse hotlines

Note: Insurance companies are not required to offer extra benefits, so some do not.

Who Is Eligible For Medicare Supplement?

As a basic rule, you must be eligible for Medicare Parts A and B in order to qualify for Medigap plans. However, Medicare Supplement eligibility is also subject to federal and state laws. This means that the federal government imposes basic regulations, and some states add additional requirements.

For instance, federal law requires that Medicare Supplement insurance plans offer coverage to people age 65 and older. However, some states require Medicare Supplement insurers to allow people younger than age 65 to enroll, if they’re eligible for Medicare.

We’ll be reviewing some of the costs of Medicare Supplement in the next section, but for now, know that Medigap coverage is usually better for those age 65 and up because premiums for people under age 65 can be expensive.

Since Medigap is designed to work with Original Medicare, you must remain enrolled in Part A and Part B at all times.

Medigap Costs

While Medicare Supplement insurance is designed to lower your out-of-pocket spending, there are certain costs that you’ll still have to pay. Your specific costs will vary based on which standardized plan you choose, but you can expect to pay some or all of Medicare Supplement costs:

  • Part B premium (paid to Social Security regardless of which Medigap plan you choose)
  • Monthly premium for Medigap coverage (paid to your insurance company and can increase over time)
  • Deductibles (Part A and/or B, or some percentage of the Part A deductible)
  • Coinsurance (whatever amount your Medigap plan doesn’t cover)

Example: Let’s say you have Medicare Supplement Plan G. Your monthly premium at age 65 might be $135 per month, in addition to your Part B premium of $148.50. You go to the doctor in January and have bloodwork, imaging (x-ray, or MRI), and a minor outpatient surgery performed. And your total Medicare-approved costs are $600.

Since Mediare Supplement Plan G doesn’t cover the Part B deductible, you must pay the first $203 for Part B expenses. Your Medigap plan will then cover the rest of your bills. And you won’t pay out of pocket for any other Medicare-approved services for the rest of the year.

When Can I Enroll in Medigap?

There are two types of enrollment into Medicare Supplement plans:

  • Guaranteed issue
  • Medically underwritten (We’ll cover these more in depth in a bit).

You’ll get a Medigap Open Enrollment Period when you meet these two criteria:

  • You are age 65, and
  • You are enrolled in Medicare Part B

Your Medicare Supplement insurance open enrollment period won’t start until both of these conditions are true. So if you work beyond age 65 and delay enrollment in Part B, your Medigap Open Enrollment Period won’t begin until you actually enroll in Part B, even if it’s after your 65th birthday. On the other hand, if you enter Medicare before you turn 65 (say, due to disability), your open enrollment period doesn’t begin until you actually turn 65.

Whenever your Medicare Supplement Open Enrollment Period begins, it will last for six months. You can enroll in any Medicare Supplement insurance plan available in your state during this time, and your enrollment is guaranteed.

Note: Your Medigap Open Enrollment Period is not the same as the Medicare Open Enrollment Period.

Medicare Supplement Guaranteed Issue

With Medicare Supplement guaranteed issue, you can’t be declined coverage, charged a higher premium based on your health status, or be subject to a waiting period.

You may have the opportunity to get Medigap coverage (or switch from one plan to another) on a guaranteed issue basis in other limited situations, including when:

  • You permanently move out of your plan’s service area.
  • You leave your first Medicare Advantage plan after trying it out for 12 months or less (Trial Right).
  • Your Medicare Advantage plan loses, or fails to renew, its contract with CMS.
  • You lose certain employer or retiree coverage.

If you don’t qualify for guaranteed issue, you’ll have to apply for a medically-underwritten Medigap policy.

Medical Underwriting

If you apply for Medicare Supplement insurance outside of your Open Enrollment period and you don’t qualify for a guaranteed issue period, you’ll be subject to medical underwriting. This means that you’ll answer questions about your health on your application. It also means you can be declined coverage for health reasons, or you can be charged a higher premium. A plan can also impose a waiting period for services relating to a pre-existing condition. This waiting period can be up to six months.

For these reasons, you are better off getting Medigap when you’re first eligible, during your Open Enrollment Period.

How Does Medigap Work with Other Insurance Plans?

Medicare Supplement insurance is designed to work with Original Medicare. You cannot combine Medigap coverage with a Medicare Advantage plan.

However, you can get drug coverage from a standalone Medicare Part D Prescription Drug Plan.

Medicare Supplement & Dual Eligibility

If you’re on Medicare and Medicaid at the same time (often called dual eligibility), you may not be able to get Medicare Supplement Insurance, except in very limited circumstances.

What’s The Difference Between Medicare Advantage And Medicare Supplement Plans?

While both of these Medicare plan types are offered through private insurance companies, they have several major differences.

Medicare Advantage plans are an alternative to Original Medicare. Meanwhile, Medigap plans are designed to work with Original Medicare. You’ll stay in Parts A and B, and Medigap supplements your coverage by paying for some or all of your out-of-pocket costs. Here is a helpful resource to learn more about the differences between Medigap and Medicare Advantage.

Many Medicare Advantage plans offer prescription drug coverage. But no modern Medicare Supplement plan (after 2006) provides drug coverage. Instead, you’ll need to combine your Medigap coverage with a Prescription Drug Plan.

Most Medicare Advantage plans are either HMOs or PPOs that use a network of doctors and facilities. Medicare Supplement insurance, though, retains all of the flexibility of Original Medicare. This means you can see any provider in the nation that takes Medicare patients. There are no plan networks, and you generally don’t need a referral to see specialists.

Advantages and Disadvantages of Medicare Supplement Plans?

Medicare Supplement plans are very useful for lowering your out-of-pocket Medicare costs, but they’re not for everyone. Here are some pros and cons.

Pros of Medicare Supplement Insurance

  • Maximum flexibility (no network or referral restrictions).
  • More comprehensive plan with less out-of-pocket expenses than Original Medicare or Medicare Advantage (depending on which Medigap policy you choose).
  • More likely to provide coverage while you’re travelling outside of the United States.

Cons of Medicare Supplement Insurance

More expensive than Original Medicare or Medicare Advantage (initial premiums are usually higher, and they rise over time). You must also get drug coverage in a separate Prescription Drug plan, which adds costs.

Medicare Supplement Plan Comparison Chart

Click here to compare 2021 Medicare Supplement plans and get a complete breakdown of benefits, coinsurance costs, and deductible amounts.

Compare Medigap Plans

In this Medicare Supplement guide, we’ve reviewed the basics of coverage and given examples of how Medigap plans work. Overall, Medicare Supplement plans can be a great way to lower or eliminate your out-of-pocket healthcare costs under Original Medicare. And these plans are especially good for those who can comfortably afford the premiums, don’t want network or referral restrictions, or travel outside of the U.S. frequently.

If you’re looking for Medicare coverage that offers more flexibility, we can help you find the right Medicare Supplement Insurance plan to fit your lifestyle.

Call 800-620-4519 (TTY 711) to speak with one of our licensed insurance agents about your Medicare Supplement plan options.

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 a donut with a bite as a visual metaphor for the Medicare Donut Hole

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