A Medicare Supplement Fills the Gaps That Original Medicare Leaves

Medicare Supplement insurance (also called Medigap) pays some of the costs that Original Medicare does not cover. Original Medicare — Parts A and B — leaves you responsible for deductibles, copayments, and coinsurance. A Medigap policy is a contract with a private insurance company that covers some or all of those out-of-pocket amounts.

You buy Medigap from a private insurer, not from Medicare. The federal government sets what each Medigap plan must cover, but the insurance company sets the price. You keep your Original Medicare coverage and pay both a Medicare premium and a Medigap premium.

Medigap does not cover prescription drugs, dental, vision, or hearing. If you need those, you would look at other coverage separately. Medigap also does not work with Medicare Advantage (Part C) — you choose either Original Medicare with a Medigap supplement, or Medicare Advantage alone.

Key Takeaways

  • Medigap is sold by private insurance companies and covers deductibles, copayments, and coinsurance that Original Medicare leaves you to pay.
  • The federal government defines ten standardized Medigap plans (A through N), so the same plan letter covers the same benefits no matter which company sells it.
  • You can enroll in Medigap during your initial Medicare enrollment period or during the annual open enrollment period, though waiting may cost you more.
  • Medigap premiums vary by age, location, and which insurance company you choose, and they increase as you get older.
  • You cannot use Medigap if you have Medicare Advantage; you must have Original Medicare (Parts A and B) to buy a supplement.

The Ten Standardized Medigap Plans and What They Cover

Medicare defines ten Medigap plans, labeled A through N. Each plan letter covers a specific set of benefits. Plan A is the most basic; plans like G and N cover more. The federal government sets what each plan must include, so Plan G from one insurance company covers exactly the same things as Plan G from another company — only the price differs.

Plan G is the most popular choice for people newly may be able to access for Medicare, because it covers most of what Original Medicare does not: the Part B deductible, copayments for hospital stays and doctor visits, and coinsurance for skilled nursing facilities. Plan N is less expensive but requires you to pay small copayments at the doctor's office and emergency room. Plan A costs less but does not cover the Part B deductible, which is $240 in 2024 (this amount changes yearly).

You can see a side-by-side comparison of all ten plans on Medicare.gov. The comparison shows exactly which costs each plan covers. Because the plans are standardized, you can compare prices from different insurance companies for the same plan letter and choose based on cost alone.

When You Can Enroll in Medigap and Why Timing Matters

Your best window to enroll in Medigap is your Medigap open enrollment period, which lasts six months and starts the month you turn 65 and enroll in Medicare Part B. During this period, insurance companies cannot deny you coverage or charge you more based on your health history — a protection called may provide issue.

If you miss this window, you can still buy Medigap later, but the insurance company may charge you more or deny you coverage if you have a pre-existing condition. Some states have additional protections that extend may provide issue, but not all. The longer you wait after your initial enrollment period, the higher your premiums are likely to be.

You can also enroll during the annual open enrollment period, which runs from October 15 to December 7 each year. During this time, you can switch from one Medigap plan to another or from one insurance company to another, though again, may provide issue protections vary by state and by how long you have been without coverage.

How Medigap Premiums Work and What Affects the Cost

Medigap premiums depend on three main factors: which plan you choose, your age, and where you live. The same plan letter costs different amounts in different states and from different insurance companies. A Plan G from Company A in Florida may cost $150 per month, while the same plan from Company B in Florida costs $180 per month.

Insurance companies use different pricing methods. Some use age-attained pricing, which means your premium goes up each year as you age. Others use issue-age pricing, which locks in a lower rate based on your age when you first buy the plan, though the rate still increases over time. A few use community-rated pricing, where everyone in your state pays the same premium regardless of age (this is rare and only available in a few states).

You pay your Medigap premium directly to the insurance company each month, separate from your Medicare Part B premium. You will receive a bill from the insurance company, not from Medicare. If you receive a subsidy for your Part B premium through a program like Medicaid, that does not help with Medigap costs.

How Medigap Works Alongside Original Medicare

When you have Medigap, you keep your Original Medicare coverage. You still see any doctor who accepts Medicare, and Medicare still pays its share of the bill first. Then your Medigap plan pays the portion that Medicare does not cover, up to the limits of your plan.

Here is how it works in practice: you go to the doctor, and the bill is $150. Medicare Part B covers 80 percent of approved services after you meet your deductible, so Medicare pays $120 and you would normally owe $30. Your Medigap plan then pays that $30 (if your plan covers it). You pay nothing out of pocket.

If you receive care from a provider who does not accept Medicare, neither Medicare nor Medigap will pay. Medigap only works with Medicare-approved providers and services. You are responsible for the full bill if you go out of network.

Medigap Does Not Cover Everything

Medigap covers the gaps in Original Medicare, but it does not cover services that Original Medicare itself does not cover. This means Medigap does not pay for prescription drugs, dental work, vision care, hearing aids, or long-term care. If you need prescription drug coverage, you must enroll in a separate Part D plan. Dental, vision, and hearing are not covered by any part of Medicare unless you have a specific condition that qualifies.

Medigap also does not cover care you receive outside the United States, except in limited situations. If you travel internationally, you would need separate travel insurance to cover medical emergencies abroad.

Some people combine Medigap with a Part D prescription drug plan and separate dental or vision insurance to cover more of their healthcare costs. Others choose Medicare Advantage instead, which bundles hospital, doctor, prescription drug, and often dental and vision coverage into one plan — though Medicare Advantage typically has higher out-of-pocket limits and requires you to use in-network providers.

Switching Plans or Insurance Companies

You can switch Medigap plans or insurance companies during the annual open enrollment period (October 15 to December 7) or if you have a may have access to life event, such as moving to a new state or losing your current coverage. If you switch during open enrollment, you have may provide issue protections in most states, meaning the new company cannot deny you or charge you more based on health.

If you switch outside of open enrollment, the new insurance company may underwrite your process, which means they review your health history and can deny you or charge you more. Some states have additional protections, but not all. Before you switch, check whether your state offers may provide issue for your situation.

When you switch plans, there may be a gap in coverage if the new plan does not start when ready. Coordinate with your current insurance company to make sure there is no lapse. You can also contact your State Health Insurance information Program (SHIP) for free help comparing plans and understanding your switching options.

Frequently Asked Questions

Can I have both Medigap and Medicare Advantage?

No. You must choose either Original Medicare with a Medigap supplement, or Medicare Advantage. If you have Medicare Advantage and buy a Medigap policy, Medicare will not pay your Medigap premiums, and the Medigap plan will not work with your Medicare Advantage coverage. You would be paying for coverage you cannot use.

What happens to my Medigap if I move to a different state?

Your Medigap policy ends when you move. You must enroll in a new Medigap plan in your new state. During your move, you have may provide issue protections for 63 days, so the new insurance company cannot deny you or charge you more based on health. After 63 days, you lose this protection. Contact your new state's SHIP program for help finding a plan.

Do I have to take a Part D drug plan if I have Medigap?

Medigap does not include prescription drug coverage, so if you want drug coverage, you must enroll in a separate Part D plan. If you do not enroll in Part D when you first become may be able to access and go without coverage for more than 63 days, you may pay a permanent penalty on your Part D premiums. You can enroll in Part D during the annual open enrollment period or if you have a may have access to life event.

What if I cannot afford the Medigap premium?

Some people with low income and limited resources may be covered by Medicaid, which can help pay Medicare premiums and cost-sharing. You would need to contact your state Medicaid office to see if you may have access to. Your SHIP program can also help you understand your options and connect you with local resources.

Can an insurance company drop me from my Medigap plan?

Insurance companies can discontinue a Medigap plan in your state, but if they do, they must offer you the chance to switch to another plan with the same company without underwriting. They cannot drop you individually because of your health or claims history. If your plan is discontinued, your state's SHIP program can help you find a new plan.