The core difference: how you pay and where you go

Medicare Supplement (also called Medigap) and Medicare Advantage are two completely different ways to cover costs after Original Medicare pays its share. The choice changes which doctors you can see, how much you pay upfront, and what happens if you need expensive care.

With Medicare Supplement, you keep Original Medicare (Parts A and B) and buy a separate insurance policy from a private company to cover what Medicare doesn't pay — copays, coinsurance, and deductibles. You can see any doctor or hospital that takes Medicare, anywhere in the country. With Medicare Advantage, you replace Original Medicare entirely with a plan run by a private insurance company. These plans usually limit you to a network of doctors and hospitals, but they often include prescription drug coverage and extras like dental or vision.

Neither is universally "better." The right choice depends on your health, how much you travel, which doctors you want to see, and how much predictability you need in your monthly costs.

Key Takeaways

  • Medicare Supplement lets you see any Medicare-accepting doctor anywhere; Medicare Advantage restricts you to a network but often costs less per month.
  • Medicare Supplement has no annual out-of-pocket limit, so catastrophic illness can mean unlimited costs; Medicare Advantage has a legal maximum you cannot exceed.
  • Medicare Supplement premiums are usually higher each month but predictable; Medicare Advantage premiums are lower but you pay more when you use care.
  • You can switch from Medicare Advantage to Medicare Supplement only during specific windows, and insurers can deny you or charge more based on health; switching from Supplement to Advantage is easier.
  • Medicare Advantage plans vary widely by region and change every year, so the plan available to you now may not exist next year.

How much you pay each month and when you use care

Medicare Supplement premiums are typically $150 to $300 per month, depending on your age, location, and which plan letter you choose (Plan A, B, C, D, and so on). Once you pay that premium, you have predictable costs: most Supplement plans cover the Medicare Part B deductible and coinsurance, so you pay little or nothing when you see a doctor. Some plans cover Part B excess charges — amounts doctors can bill above Medicare's approved rate — which Original Medicare does not cover at all.

Medicare Advantage premiums are often $0 to $50 per month, which sounds cheaper. But when you use care, you pay copays (a flat amount per visit) or coinsurance (a percentage of the cost). A specialist visit might cost $40 to $60 out of pocket. An emergency room visit might cost $250 to $500. These costs add up, and they count toward your annual out-of-pocket maximum — usually $6,700 to $7,500 for in-network care. Once you hit that limit, the plan pays 100% of covered in-network costs for the rest of the year.

The trade-off: Supplement plans have no out-of-pocket maximum, so if you need major surgery or long-term treatment, your costs are capped only by what the plan covers. Advantage plans have a legal ceiling on what you pay, but you reach it only if you use a lot of care.

Network restrictions and where you can get care

With Medicare Supplement, you can see any doctor, specialist, or hospital that accepts Medicare and accepts Medigap. That includes providers across the country. If you travel frequently, spend winters in another state, or want to keep your longtime doctor even if they move, Supplement gives you that freedom. You do not need referrals, and you do not have to call ahead for permission to see a specialist.

Medicare Advantage plans have a network — a list of doctors, hospitals, and other providers you should use. If you see an out-of-network provider, you pay much more (sometimes the full bill), unless it is an emergency. Some plans are HMOs, which require you to pick a primary care doctor and get referrals to see specialists. Others are PPOs, which let you see specialists without a referral but still charge more for out-of-network care. A few plans are regional, covering only certain counties or states.

This matters most if you have a doctor you trust and want to keep, if you live part of the year in multiple states, or if you travel often. It also matters if you live in a rural area where the Advantage network is thin.

Prescription drugs, dental, vision, and other extras

Original Medicare does not cover prescription drugs. If you have a Supplement plan, you must buy a separate Part D prescription drug plan. You pay a monthly premium for Part D (usually $10 to $50), and you pay copays when you fill prescriptions. You can choose any Part D plan available in your area, and you can switch plans every year during open enrollment.

Medicare Advantage plans almost always include prescription drug coverage built in — you do not buy Part D separately. The copays for drugs are usually similar to standalone Part D plans, but they are bundled into one plan, which can be simpler to manage.

Many Medicare Advantage plans also include dental, vision, hearing aids, or fitness benefits that Original Medicare and Supplement plans do not cover. These extras can save you money if you use them. However, these benefits vary widely by plan and by region. The plan you have access to in your area might not include the extras you want.

Switching plans and what happens if your health changes

If you have a Medicare Supplement plan and want to switch to a different Supplement plan, you can do so any time. The new insurer cannot deny you or charge you more based on your health — this is called may provide issue. However, if you want to switch from Medicare Supplement to Medicare Advantage, you can do so only during the annual enrollment period (October 15 to December 7) or if you may have access to for a special enrollment period. Once you switch away from Supplement, you may not be able to get back into Supplement later, depending on your health and your state's rules.

If you have Medicare Advantage and want to switch to a different Advantage plan, you can do so during open enrollment. If you want to switch to Medicare Supplement, you can do so during open enrollment, but the Supplement insurer can deny you or charge you more based on your health — unless you may have access to for a may provide issue period. may provide issue periods include losing your Advantage plan's coverage, moving out of the plan's service area, or having your plan end.

This asymmetry is important: it is easier to move between Supplement plans or to stay in Supplement than to leave it and come back.

Stability and what changes year to year

Medicare Supplement plans are standardized by the federal government. Plan A covers the same things whether you buy it from Insurer X or Insurer Y. The plan design does not change. What does change is the premium — insurers can raise rates, and rates vary by location and age. But the coverage itself stays the same year to year.

Medicare Advantage plans change constantly. Every year, insurers can change the copays, the network, the out-of-pocket maximum, and which drugs are covered. A plan you liked this year might not exist next year, or it might change so much that it no longer suits you. You have to review your plan every year during open enrollment to see if it still makes sense for you.

If you value knowing exactly what your coverage will be next year, Supplement offers more stability. If you are willing to shop your plan annually and adapt, Advantage can work.

Which choice makes sense for different situations

Medicare Supplement may be better if: You have a doctor or hospital you want to keep seeing and they are not in every Advantage network. You travel frequently or split time between states. You have a chronic condition that requires many specialist visits and you want to avoid copays. You want predictable monthly costs and do not want to shop plans every year. You are comfortable paying higher premiums to have fewer surprises.

Medicare Advantage may be better if: You are healthy and do not expect to use much care. You want a low or zero monthly premium. You want dental, vision, or hearing coverage included. You live in an urban area with a robust network. You are willing to review your plan every year. You want a legal cap on how much you can spend out of pocket in a year.

There is no single right answer. The choice depends on your health, your doctors, your budget, and how much uncertainty you can tolerate.

Frequently Asked Questions

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

No. You must choose one or the other. If you enroll in Medicare Advantage, your Original Medicare coverage ends. If you later switch back to Original Medicare and Supplement, you cannot have Advantage at the same time.

What if my Medicare Advantage plan drops out of my area?

If your plan ends or leaves your region, you have a special enrollment period to switch to a different Advantage plan or to Medicare Supplement without waiting for open enrollment. You will also have may provide issue rights to Supplement, meaning the insurer cannot deny you based on health.

Do I need to choose between Supplement and Advantage when I first turn 65?

You have a window when you first enroll in Medicare Part B to buy a Supplement plan with may provide issue — you cannot be denied or charged more based on health. After that window closes, may provide issue becomes harder to get. This makes the initial choice important, though you can still switch later during open enrollment.

Will my Supplement premium keep going up every year?

Yes, Supplement premiums typically increase each year due to age and inflation. However, the rate of increase varies by insurer and plan. Some insurers use "issue age" pricing (your premium is based on your age when you buy the plan and increases slowly), while others use "attained age" pricing (your premium increases faster as you get older). You can compare rates from different insurers and switch Supplement plans if a competitor offers a better price.

What happens if I need care outside the United States?

Original Medicare and most Medicare Supplement plans do not cover care outside the U.S., though some Supplement plans offer limited emergency coverage abroad. Medicare Advantage plans typically do not cover care outside the U.S. either. If you travel internationally, check your plan's coverage before you go.