The core difference between Medigap and Medicare Advantage

Medigap (also called Supplement Insurance) works alongside Original Medicare. It pays some of the costs that Medicare does not — copayments, coinsurance, and deductibles. You keep your Original Medicare coverage and add a Medigap policy on top. You can see any doctor or hospital that accepts Medicare.

Medicare Advantage (also called Part C) replaces Original Medicare entirely. It is run by private insurance companies and typically includes prescription drug coverage built in. In exchange, you usually have a network — you must see doctors in that network, except in emergencies. Most plans have lower monthly premiums than Medigap, but you pay more when you use care.

Neither is objectively "better." The right choice depends on your health, your doctors, how much you travel, and what you can afford to pay out of pocket when you need care.

Key Takeaways

  • Medigap lets you see any Medicare-accepting doctor and covers most out-of-pocket costs, but premiums are higher and you must buy a separate prescription drug plan.
  • Medicare Advantage has lower premiums and includes prescription drugs, but limits you to in-network doctors and charges copays and coinsurance when you use care.
  • If you have ongoing relationships with specific doctors or specialists, Medigap usually costs less overall because you avoid network restrictions.
  • If you are generally healthy and do not see doctors often, Medicare Advantage premiums may save you money despite higher per-visit costs.
  • You can switch between Medigap and Medicare Advantage only during specific enrollment windows, so the choice matters for at least a year.

How costs work under each plan

Medigap premiums vary by age, location, and which plan letter you choose (Plan A, B, C, D, and so on). Plans with higher premiums cover more of your out-of-pocket costs. Once you pay your monthly premium, most Medigap plans cover your Medicare copayments and coinsurance almost entirely — you go to the doctor and pay little or nothing at the visit. You do pay for prescription drugs separately through a Part D plan, which has its own monthly premium and cost structure.

Medicare Advantage premiums are often lower — some plans charge zero monthly premium — but you pay when you use care. A visit to your primary care doctor might cost $15 to $25. A specialist visit might cost $40 to $75. Hospital stays, imaging, and procedures have separate copays or coinsurance. Most plans cap your out-of-pocket spending each year (for 2024, the maximum is set by Medicare and varies by plan), but you pay up to that cap before the plan covers everything else.

The math depends on how often you see doctors. If you see a specialist monthly, Medigap usually costs less overall. If you see a doctor once a year, Medicare Advantage premiums may win.

Network restrictions and doctor choice

With Medigap, you can see any doctor, hospital, or specialist in the United States who accepts Medicare. You do not need referrals. You do not need to check a network. This matters most if you have a long-standing relationship with a doctor, if you see multiple specialists, or if you travel and want to know you can see a doctor anywhere.

Medicare Advantage plans have networks. You must see doctors in that network for regular care, or you pay much more (sometimes the full cost). Some plans require you to choose a primary care doctor and get referrals to see specialists. Emergency care is covered anywhere, but urgent care outside the network may not be. If your current doctors are not in the plan's network, switching to Medicare Advantage means finding new doctors or paying out of network.

Before choosing Medicare Advantage, check whether your doctors are in the plan. Call your doctor's office and ask directly — do not rely on the insurance company's online directory alone, because those lists are often outdated.

Prescription drug coverage

Medicare Advantage plans include prescription drug coverage (Part D) as part of the plan. You pay one premium and one deductible. The plan's formulary (the list of drugs it covers) varies, so check whether your medications are on it and at what tier (cost level).

If you choose Medigap, you must buy a separate Part D prescription drug plan. You pay two premiums — one for Medigap and one for Part D. You have more choice in which drug plan you pick, and you can switch Part D plans every year during the annual enrollment period without penalty. With Medicare Advantage, switching drug coverage usually means switching the entire plan.

If you take many medications or expensive drugs, compare the total cost of Medigap plus Part D against the Medicare Advantage plan's formulary and copays. Sometimes one is clearly cheaper; sometimes they are close.

When you can switch and what it costs

You can change from Medigap to Medicare Advantage or vice versa, but only during specific windows. The main window is the Annual Enrollment Period (AEP), which runs October 15 to December 7 each year. Changes take effect January 1. During this window, you can switch without medical underwriting — the insurance company cannot deny you or charge more based on your health.

Outside AEP, switching is harder. If you move to Medicare Advantage and later want to go back to Medigap, you may face medical underwriting (the company can deny you or charge more if you have health conditions). Some states have protections that limit this, but not all. If you switch from Medigap to Medicare Advantage, you might not be able to get Medigap back at the same price.

This is why the choice matters: you are usually locked in for at least a year. If you pick wrong, you may pay a penalty in higher premiums or denied coverage if you try to switch back.

Special situations: when one plan makes more sense

Choose Medigap if: You have multiple chronic conditions or see specialists regularly. You want to keep your current doctors without checking networks. You travel frequently or live part of the year in different states. You want predictable costs with minimal copays. You prefer the freedom to see any doctor without referrals.

Choose Medicare Advantage if: You are generally healthy and see doctors rarely. You want the lowest possible monthly premium. You are willing to use in-network doctors. You want prescription drugs included in one plan. You do not mind paying per visit or per service. You want extra benefits like dental, vision, or fitness programs (many Medicare Advantage plans include these; Medigap does not).

If you have End-Stage Renal Disease (ESRD), certain disabilities, or are under 65, Medicare Advantage rules are different — talk to your Social Security office or Medicare directly about your options.

Questions to ask your doctor and Medicare

Before you decide, contact your doctors' offices and ask: "Are you accepting new Medicare Advantage patients? Which Medicare Advantage plans do you participate in?" Write down the plan names. Then check those specific plans' formularies for your medications.

Call Medicare at 1-800-MEDICARE (1-800-633-4227) and ask: "What is my out-of-pocket maximum under Medicare Advantage? What is the average cost of my medications under each plan's formulary?" Request a personalized comparison of Medigap plans and Medicare Advantage plans available in your area. You can also visit Medicare.gov and use the Plan Finder tool to compare plans side by side.

Frequently Asked Questions

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

No. You must choose one or the other. If you enroll in Medicare Advantage, your Medigap policy will be canceled (or you should cancel it to stop paying the premium). If you have Medicare Advantage and buy Medigap, Medicare will not pay the Medigap claim because you are not on Original Medicare.

What happens to my Medigap coverage if I switch to Medicare Advantage?

Your Medigap policy ends. If you want to go back to Medigap later, you may face medical underwriting and higher premiums, depending on your state and health. Some states have protections that allow you to return to Medigap without underwriting within a certain time frame — check with your state insurance commissioner's office.

Do Medicare Advantage plans cover out-of-network emergency care?

Yes, emergency room visits are covered anywhere, even out of network. However, follow-up care after the emergency may require you to return to an in-network provider. Urgent care (not emergency) outside the network may not be covered or may be covered at a higher cost — check your plan's rules.

Can I change my mind during the year if I pick the wrong plan?

You can make changes only during the Annual Enrollment Period (October 15 to December 7) or if you have a may have access to life event (moving, losing other coverage, getting married). Outside these windows, you are locked into your plan until the next AEP.

Which plan is cheaper if I take a lot of medications?

It depends on the specific medications and the plans available to you. Some Medicare Advantage plans have low copays for common drugs; others have high copays for specialty medications. Compare your actual drug list against each plan's formulary and copay tiers. Medicare.gov's Plan Finder lets you enter your medications and see estimated costs for each plan.