The core difference: how each plan pays your medical bills

Medigap and Medicare Advantage are two different ways to cover costs that Original Medicare (Part A and Part B) does not pay. They work in opposite directions, and which one makes sense depends on how you use healthcare and what trade-offs matter to you.

With Medigap, you keep Original Medicare and buy a separate insurance policy from a private company. That policy covers some or all of the costs Medicare leaves behind — copayments, coinsurance, and deductibles. You can see any doctor or hospital that accepts Medicare, anywhere in the country. With Medigap, you pay a monthly premium for the supplemental policy, plus your Original Medicare Part B premium.

With Medicare Advantage, you replace Original Medicare entirely. A private insurance company runs your plan and decides which doctors, hospitals, and specialists are in-network. Most Advantage plans include prescription drug coverage (Part D) built in, and many add dental, vision, or hearing benefits. You pay a monthly premium (sometimes zero), plus copayments when you use care. You are locked into that plan's network, with few exceptions.

Key Takeaways

  • Medigap lets you see any Medicare-accepting doctor anywhere; Medicare Advantage restricts you to in-network providers but often costs less per month and includes prescription drugs.
  • Medigap premiums are predictable and do not change based on how much healthcare you use; Medicare Advantage premiums are lower but you pay per visit through copayments.
  • Medigap plans are standardized by the federal government, so Plan G from one company covers the same things as Plan G from another; Medicare Advantage plans vary widely by insurer and region.
  • Medicare Advantage plans have annual out-of-pocket limits that cap your total costs; Medigap does not, though premiums tend to be higher.
  • Switching between Medigap and Medicare Advantage is easiest during your initial enrollment window or during the annual open enrollment period in fall.

When Medigap makes sense: predictable costs and doctor choice

Medigap is the right choice if you see doctors regularly, have chronic conditions, or travel frequently. Because you keep Original Medicare, any doctor or hospital in the country that accepts Medicare must accept you — no referrals, no network restrictions. If you have a preferred cardiologist in another state or want to see a specialist without asking permission, Medigap gives you that freedom.

Your costs are also predictable. You know your monthly premium in advance, and it does not change based on how sick you are or how many times you go to the doctor. Once you have paid your deductible (which varies by plan type), your Medigap policy covers the rest. This matters if you have multiple chronic conditions or take many medications — you can budget for healthcare without surprises.

Medigap plans are standardized by the federal government. There are ten plan types (A, B, D, G, K, L, M, N, and two others), and Plan G from Blue Cross covers exactly the same things as Plan G from Aetna. You choose based on price and company reputation, not because plans differ. Plan G and Plan N are the most common for new enrollees because they cover most costs after the deductible.

The trade-off is cost. Medigap premiums are typically higher than Medicare Advantage premiums, especially if you are healthy and do not use much care. You also pay for prescription drugs separately through Part D, which adds another monthly premium.

When Medicare Advantage makes sense: lower premiums and extra benefits

Medicare Advantage is the right choice if you want to minimize monthly premiums, do not mind using in-network doctors, or value dental and vision coverage. Many Advantage plans charge zero monthly premium — you pay only when you use care. Even plans with a premium often cost less per month than Medigap plus Part D combined.

Most Medicare Advantage plans include prescription drug coverage, dental, vision, and hearing benefits at no extra cost. If you need regular dental work, new glasses, or a hearing aid, those benefits can save you hundreds of dollars per year compared to paying out of pocket or buying separate policies.

Medicare Advantage plans have an annual out-of-pocket maximum — a cap on how much you will pay in copayments and coinsurance in a year. Once you hit that limit, the plan pays 100 percent of covered services for the rest of the year. With Medigap, there is no such cap, though your total costs (premiums plus out-of-pocket) are often lower if you use little care.

The trade-off is flexibility. You must use in-network doctors and hospitals, except in emergencies. If you travel out of state for months at a time, or if your specialist is out of network, an Advantage plan becomes expensive or impossible to use. You also cannot see a specialist without a referral from your primary care doctor on most plans.

Comparing costs: the math depends on your health

If you are healthy and rarely see a doctor, Medicare Advantage usually costs less. A zero-premium plan with a $200 copay per visit is cheaper than a $150-per-month Medigap premium plus a $35-per-month Part D premium if you visit the doctor twice a year.

If you have multiple chronic conditions or see specialists regularly, Medigap often costs less overall. A $200-per-month Medigap premium plus $40-per-month Part D is $2,880 per year. A Medicare Advantage plan with a $50 copay per visit and $250 copay per specialist visit adds up quickly if you see your cardiologist four times a year, your rheumatologist four times, and your primary doctor six times — that is $1,500 in copays alone, plus the monthly premium.

Costs vary by region, by insurer, and by plan. There is no national answer. The only way to know which costs less for you is to get quotes from both types of plans in your area and add up what you would actually pay based on the doctors you see and the care you use.

Network and travel: freedom versus savings

Medigap gives you complete freedom to travel. Because you keep Original Medicare, you can see any Medicare-accepting doctor anywhere in the United States without notifying your insurance company. If you spend winters in Arizona and summers in Maine, Medigap works the same in both places.

Medicare Advantage ties you to a specific region. Most plans cover only in-network providers in their service area. If you travel out of state for a few weeks, you can use emergency care, but routine visits are not covered. If you move permanently, you can switch plans during the annual open enrollment period, but you cannot straightforward keep your current plan in a new state.

Some Medicare Advantage plans offer out-of-network emergency coverage or temporary out-of-area coverage for travel, but the details vary by plan. Read the plan documents before enrolling if travel matters to you.

Switching between plans: timing and rules

You can switch from Medicare Advantage to Medigap or from Medigap to Medicare Advantage, but the timing matters. During your initial enrollment window (the three months before and after you turn 65 or become may be able to access for Medicare), you can switch without restrictions or waiting periods.

After that window closes, you can switch during the annual open enrollment period from October 15 to December 7 each year. Changes take effect January 1. You can also switch if you move out of your plan's service area or if your plan is discontinued.

If you switch from Medicare Advantage to Medigap outside the initial enrollment window, some insurance companies may deny you coverage or charge higher premiums based on your health history — a practice called underwriting. Switching from Medigap to Medicare Advantage has no such penalty; Medicare Advantage plans must accept you regardless of health.

Prescription drug coverage: included or separate

Medicare Advantage plans almost always include prescription drug coverage (Part D). You pay a copay when you fill a prescription, and the plan covers the rest up to the annual out-of-pocket limit.

If you choose Medigap, you must buy Part D separately from a private insurance company. You pay a monthly premium for Part D plus copayments at the pharmacy. You can change your Part D plan once per year during the annual open enrollment period, which is useful if your medications change or if a cheaper plan becomes available.

Part D plans vary in which drugs they cover and at what cost. If you take expensive medications, compare Part D plans carefully — the cheapest premium is not always the cheapest plan for your specific drugs.

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 terminated. If you buy Medigap, you cannot use Medicare Advantage. You can switch between them during open enrollment, but you cannot hold both simultaneously.

What happens to my Medicare Advantage plan if I move to a different state?

Your plan will end on December 31 of the year you move. You can enroll in a new Medicare Advantage plan in your new state during the annual open enrollment period, or you can switch to Medigap. You have a special enrollment period to make this change outside the normal enrollment window.

Do I need to see a primary care doctor with Medigap?

No. With Medigap, you keep Original Medicare, which has no primary care requirement. You can see any specialist directly without a referral. Medicare Advantage plans usually require a primary care doctor and referrals to specialists, though some plans are less restrictive than others.

Which plan is better for someone with cancer or a serious illness?

Medigap is usually better for serious illnesses because you can see any doctor, change specialists without referrals, and your costs are capped by your monthly premium rather than by visit. Medicare Advantage can work if your doctors are in-network, but switching doctors or seeking a second opinion may be more complicated and expensive.

Can I switch from Medicare Advantage to Medigap if I have a pre-existing condition?

During your initial enrollment window, yes, with no restrictions. After that window, some Medigap insurers may underwrite your process and deny coverage or charge more based on your health. Medicare Advantage plans cannot do this — they must accept you regardless of health status.