Medigap plans do not add new benefits — they pay the costs that Original Medicare leaves you responsible for

A Medigap plan (also called Medigap insurance or supplemental insurance) covers the deductibles, copayments, and coinsurance that Original Medicare requires you to pay out of your own pocket. It does not expand what Original Medicare covers. If Original Medicare does not pay for a service, Medigap will not pay for it either.

The main reason people buy Medigap is to reduce their share of costs for services Original Medicare already covers. For example, Original Medicare covers a hospital stay, but you pay a deductible. A Medigap plan can pay that deductible for you. Original Medicare covers doctor visits at 80 percent after you meet your deductible, and you pay the remaining 20 percent. A Medigap plan can cover that 20 percent.

Medigap plans are standardized by federal law, which means every insurance company selling Plan G, for example, must cover the same benefits. The difference between companies is the monthly premium you pay, not what the plan covers.

Key Takeaways

  • Medigap covers the out-of-pocket costs (deductibles, copayments, coinsurance) that Original Medicare requires you to pay, but does not add new covered services.
  • Original Medicare must cover a service first — Medigap then pays your share of the cost for services Original Medicare already pays for.
  • Ten standardized Medigap plans exist (A, B, D, G, K, L, M, N, and two others), and each plan covers the same benefits no matter which insurance company sells it.
  • Medigap does not cover prescription drugs, dental, vision, hearing aids, or long-term care — you need separate coverage or to pay out of pocket for these.
  • You can only buy Medigap during your open enrollment period (the six months after you turn 65 and enroll in Medicare Part B), or you may face higher premiums or denial.

The ten standardized Medigap plans and what they cover

The ten plans are labeled A, B, D, G, K, L, M, N, and two others. Each plan covers a different combination of the costs that Original Medicare leaves you responsible for. Plan G is the most popular because it covers most out-of-pocket costs, but it is also more expensive than plans like A or N.

All Medigap plans cover the same thing within their category: Part A hospital deductible, Part B coinsurance, blood transfusions, and skilled nursing facility coinsurance. Plans differ in whether they cover the Part B deductible (Plan B and G do; most others do not), whether they cover excess charges when a doctor does not accept Medicare's approved amount, and whether they cover foreign travel emergencies.

The best plan for you depends on how much you use healthcare and how much premium you can afford. Someone who sees doctors frequently and wants predictable costs might choose Plan G. Someone who rarely uses healthcare might choose Plan A or N to keep the monthly premium low.

What Medigap does not cover

Medigap does not cover prescription drugs. You need a separate Part D plan (prescription drug coverage) for that. Medigap also does not cover dental work, vision care, hearing aids, or long-term care such as nursing home or home health aide services. These are gaps in Original Medicare that Medigap cannot fill.

If you need dental or vision coverage, you can buy a standalone dental or vision plan, but these are separate from both Medicare and Medigap. Long-term care is typically covered by a separate long-term care insurance policy, which you would have bought before you turned 65 (Medicare does not cover it at any age).

How Medigap differs from Medicare Advantage

Medigap and Medicare Advantage are two different ways to get coverage beyond Original Medicare, and you cannot have both at the same time. Medicare Advantage (Part C) is an alternative to Original Medicare run by private insurance companies. It usually includes prescription drug coverage, dental, and vision, but it has network restrictions and requires you to use in-network doctors.

Medigap works alongside Original Medicare. You keep your Original Medicare coverage and your choice of any doctor who accepts Medicare. Medigap straightforward pays the costs Original Medicare leaves you responsible for. There are no networks, no referrals needed, and no prior authorization for most services.

If you have Medigap, you cannot also have Medicare Advantage. If you have Medicare Advantage and want to switch to Original Medicare with Medigap, you can do so during the annual open enrollment period (October 15 to December 7), but you may not be able to buy Medigap at standard rates if you wait past your initial enrollment window.

When you can buy Medigap and what happens if you miss the important date

The best time to buy Medigap is during your Medigap open enrollment period, which lasts six months starting the month you turn 65 and enroll in Medicare Part B. During this window, insurance companies must sell you any Medigap plan at the standard rate, regardless of your health history. This is called may provide issue.

If you do not buy Medigap during this six-month window, you can still buy it later, but the insurance company can charge you more based on your age and health conditions. Some companies may deny you coverage altogether if you have certain pre-existing conditions. The longer you wait, the more expensive Medigap becomes.

If you had group health coverage through an employer when you turned 65, you may have a different enrollment period. Ask your employer's benefits office or call Medicare at 1-800-MEDICARE to find out when your window opens.

How much Medigap costs and how premiums are set

Medigap premiums vary by plan, insurance company, your age, and where you live. Plan A is usually the least expensive. Plan G is usually more expensive but covers more costs. A 65-year-old in one state might pay $100 a month for Plan A and $200 a month for Plan G, while someone in another state might pay $80 or $250 for the same plans.

Insurance companies use three methods to set Medigap premiums: community-rated (everyone in your area pays the same regardless of age), issue-age-rated (your rate is based on your age when you buy the plan and stays the same as you age), and attained-age-rated (your rate increases as you get older). Attained-age-rated plans are usually cheaper at first but cost more over time.

You should compare quotes from at least three insurance companies in your area before you buy. The same plan from different companies can cost hundreds of dollars per year more or less. Medicare.gov has a tool to compare plans and prices in your area.

Questions to ask your doctor or Medicare counselor

Before you choose a Medigap plan, ask your doctor which services you are likely to use in the next year — hospital stays, specialist visits, lab work, imaging. This helps you understand which plan would save you the most money. Ask whether your doctor accepts Medicare and whether they have any restrictions on which insurance companies they work with (most do not, but it is worth checking).

If you are unsure whether to buy Medigap or Medicare Advantage, ask your doctor whether they participate in Medicare Advantage networks in your area. If your preferred doctors do not, Medigap may be a better fit.

You can also call your State Health Insurance information Program (SHIP) for free, unbiased counseling about which plan might work for your situation. Find your state's SHIP by calling 1-800-MEDICARE or visiting shiptalk.org.

When to contact Medicare or your insurance company

Contact Medicare (1-800-MEDICARE) if you are within six months of turning 65 and want to know your Medigap options, if you are unsure whether you are in your open enrollment period, or if you want to switch from Medicare Advantage to Original Medicare with Medigap.

Contact your Medigap insurance company if you have questions about what a specific plan covers, if you want to change plans, or if you have a claim that was denied. You can change Medigap plans once per year during the annual open enrollment period (October 15 to December 7), though you may face higher premiums if you switch to a more expensive plan.

Frequently Asked Questions

Does Medigap cover services that Original Medicare does not cover?

No. Medigap only pays the out-of-pocket costs for services Original Medicare already covers. If Original Medicare does not cover a service (such as dental work or long-term care), Medigap will not cover it either. You would need separate coverage for those services.

Can I have both Medigap and Medicare Advantage at the same time?

No. You must choose one or the other. If you have Medicare Advantage and want to switch to Original Medicare with Medigap, you can do so during the annual open enrollment period, but you should act quickly because your Medigap open enrollment period may have already passed.

What if I buy Medigap after my six-month open enrollment period ends?

You can still buy Medigap, but the insurance company can charge you more based on your age and health. Some companies may deny you coverage. The longer you wait, the more expensive it becomes, so it is best to buy during your open enrollment period if possible.

Does Medigap include prescription drug coverage?

No. You need a separate Part D plan for prescription drugs. You can buy Part D at the same time you buy Medigap, and you should enroll in Part D during your initial enrollment period to avoid a late-enrollment penalty.

How do I know which Medigap plan is right for me?

Compare plans based on how much healthcare you use and how much premium you can afford. Plan G covers the most costs but costs more. Plan A costs less but leaves you responsible for more out-of-pocket expenses. Your State Health Insurance information Program (SHIP) offers free counseling to help you decide.