Medicare Advantage vs. Medigap: Which Plan Covers What

The Core Difference: How Each Plan Works

Medicare Advantage and Medigap are two different ways to get coverage beyond Original Medicare. They work in opposite directions, which is why you cannot have both at the same time.

Medicare Advantage is an alternative to Original Medicare itself. You enroll in a private insurance plan (usually run by an insurance company) that contracts with Medicare to provide your Part A and Part B coverage. The plan sets its own rules: which doctors you can see, which hospitals you can use, whether you need referrals, and what you pay out of pocket. In exchange, Medicare Advantage plans often include prescription drug coverage (Part D) and extras like dental or vision — things Original Medicare does not cover.

Medigap is a supplement to Original Medicare. You keep your Original Medicare coverage exactly as it is, and you buy a separate policy from a private insurance company to cover the gaps — the deductibles, copayments, and coinsurance that Medicare does not pay. Medigap does not change which doctors you can see or add new benefits like dental. It straightforward pays the bills that Medicare leaves behind.

Key Takeaways

Medicare Advantage replaces Original Medicare with a private plan that includes Part A, Part B, and usually Part D, while Medigap supplements Original Medicare by paying the costs Medicare does not cover.
Medicare Advantage plans have networks (doctors and hospitals you must use), copayments, and out-of-pocket maximums, while Medigap plans let you see any doctor who accepts Medicare and have predictable costs.
Medicare Advantage often includes dental, vision, and hearing coverage; Medigap does not add any new benefits beyond paying Medicare's gaps.
You can switch between Medicare Advantage and Medigap during the annual enrollment period (October 15 to December 7), but switching can be difficult if you have health problems.
If you travel frequently or see specialists outside your area, Medigap is usually simpler; if you want dental coverage and lower premiums, Medicare Advantage may cost less upfront.

How Networks and Doctor Choice Work

Medicare Advantage plans operate like traditional health insurance: they have a network of doctors, hospitals, and specialists. If you see someone outside the network, you pay more or the plan may not cover it at all. Some plans are HMOs (Health Maintenance Organizations), which require you to pick a primary care doctor and get referrals to see specialists. Others are PPOs (Preferred Provider Organizations), which let you see specialists without a referral but still charge more for out-of-network care.

Medigap has no network. Any doctor or hospital in the United States that accepts Medicare will accept your Medigap plan. You do not need referrals. You do not have to choose a primary care doctor. This matters most if you travel, move, or see specialists in different cities.

Original Medicare itself has no network either — it is accepted nationwide — so when you add Medigap, you keep that freedom. The trade-off is that Medigap premiums are usually higher than Medicare Advantage premiums, sometimes significantly.

Out-of-Pocket Costs and Predictability

Medicare Advantage plans have an annual out-of-pocket maximum. Once you reach it (by paying copayments, coinsurance, and deductibles), the plan pays 100 percent of covered services for the rest of that year. This maximum varies by plan and by year, but it gives you a ceiling on what you will spend. However, you pay as you go: a copayment at each doctor visit, a copayment for each prescription, and so on.

Medigap plans vary by letter (Plan A, Plan B, Plan C, Plan D, and so on). Each letter covers a different set of Medicare's gaps. Some Medigap plans cover the Part B deductible; some cover coinsurance for hospital stays; some cover all of it. Once you understand which plan letter you have, your costs are highly predictable: you pay your Medigap premium each month, and then you pay only what Medicare does not cover — which is often very little or nothing, depending on your plan letter.

The catch with Medigap is that premiums can rise with age or when the insurance company raises rates for everyone. You are not capped the way you are with Medicare Advantage's out-of-pocket maximum.

Prescription Drug Coverage

Most Medicare Advantage plans include prescription drug coverage (Part D) as part of the plan. You pay a copayment for each prescription, and the plan covers the rest up to its limits. If you choose a Medicare Advantage plan without drug coverage, you must enroll in a standalone Part D plan.

If you have Original Medicare and Medigap, you must enroll in a standalone Part D plan separately. Medigap does not include drug coverage. You pay the Part D premium to one insurance company and the Medigap premium to another. This means more paperwork, but it also means you can choose your drug plan independently of your Medigap plan.

Extra Benefits: Dental, Vision, Hearing, and Fitness

Medicare Advantage plans often include benefits that Original Medicare and Medigap do not: dental cleanings and exams, vision exams and eyeglasses, hearing exams and hearing aids, and fitness programs. These are not required — plans vary widely — but many plans offer them. Some are covered in full; others have limits or require copayments.

Medigap does not add any new benefits. It only pays the costs that Medicare leaves behind. If you want dental or vision coverage with Medigap, you must buy those separately from a dental or vision insurance company, which is usually more expensive than the dental or vision benefit bundled into a Medicare Advantage plan.

Switching Plans and Enrollment Periods

You can change from Medicare Advantage to Medigap, or from Medigap to Medicare Advantage, during the annual open enrollment period from October 15 to December 7 each year. Changes take effect January 1.

If you are switching from Medicare Advantage to Medigap, insurance companies can ask health questions and may deny you or charge more based on your health history — unless you switch during a special enrollment period (such as when you move out of your plan's service area or lose employer coverage). If you are switching from Medigap to Medicare Advantage, you cannot be denied based on health, but you may lose some of the Medigap benefits you had.

The first time you become may be able to access for Medicare, you have a one-time window to enroll in Medigap without health questions, even if you have pre-existing conditions. This window is usually 63 days after you enroll in Part B. If you miss it and later want to switch from Medicare Advantage to Medigap, you may face health underwriting.

Which Plan Might Work Better for Different Situations

Medicare Advantage often makes sense if you want lower monthly premiums, do not mind using a specific network of doctors, and want dental or vision coverage included. It works well if you live in one place, see doctors within the plan's service area, and are comfortable with copayments at each visit.

Medigap often makes sense if you travel frequently, see specialists in different cities, want to see any doctor without restrictions, or prefer predictable costs with no surprises. It works well if you have established relationships with doctors outside a single network and want the freedom to keep seeing them.

Your choice also depends on your health. If you have chronic conditions and see many specialists, the lack of a network with Medigap can be valuable. If you are generally healthy and want to minimize premiums, Medicare Advantage may save you money.

Frequently Asked Questions

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

No. Medicare rules prohibit enrolling in both. If you are in a Medicare Advantage plan and want Medigap, you must first disenroll from Medicare Advantage and switch back to Original Medicare. The reverse is also true: if you have Medigap and Original Medicare, you cannot enroll in Medicare Advantage without dropping Medigap first.

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

If you have Medicare Advantage, your plan may not be available in your new state, or the plan may have a different network. You can switch to a different Medicare Advantage plan or to Medigap during your move. If you have Medigap, your coverage works in any state because there is no network — but your premium may change based on your new location.

Do I still pay Medicare premiums if I choose Medicare Advantage?

Yes. You pay the Part B premium to Medicare (the same amount as Original Medicare), plus the Medicare Advantage plan premium to the insurance company. Many Medicare Advantage plans have a zero premium, meaning you pay only the Part B premium, but some plans charge an additional monthly premium.

What if my doctor is not in my Medicare Advantage plan's network?

You can usually still see the doctor, but you will pay more out of pocket. In an HMO plan, out-of-network care may not be covered at all except in emergencies. In a PPO plan, out-of-network care is covered but at a higher copayment or coinsurance. You should check your plan's rules before scheduling an appointment.

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

During the annual open enrollment period (October 15 to December 7), you can switch, but the Medigap insurance company can ask health questions and may deny you or charge more. If you are within 63 days of first enrolling in Part B, you have a may provide right to buy Medigap without health questions. Otherwise, switching may be difficult if you have health problems.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.