Medicare Advantage vs. Medigap: How the Two Actually Compare

Medicare Advantage and Original Medicare paired with a Medigap policy are two different ways of covering the same underlying benefit. Advantage plans typically carry a lower monthly premium but require you to use a defined network of doctors and hospitals. Medigap plans typically carry a higher monthly premium but let you see nearly any provider who accepts Medicare, with little left for you to pay out of pocket. Neither is better for everyone. Which one fits depends on your health, how often you travel, which doctors you want to keep, and what you can afford month to month versus if a bad year happens.

Two different structures, not two versions of the same plan

Original Medicare is the federal program itself: Part A for hospital care, Part B for outpatient and medical care. On its own, Original Medicare has no cap on what you could pay out of pocket in a year, and it covers about 80 percent of most Part B costs, leaving you responsible for the rest. A Medigap policy, sold by private insurers but standardized by Medicare.gov, is built to fill that gap, hence the name — it pays some or most of the costs Original Medicare leaves behind.

Medicare Advantage, also called Part C, is a different arrangement entirely. Instead of Original Medicare plus a supplement, you get your Part A and Part B benefits through a private insurance company that contracts with Medicare. Most Advantage plans also bundle in Part D drug coverage and often extra benefits like dental or vision. The plan sets its own network of providers, its own cost-sharing structure, and, unlike Original Medicare, an annual out-of-pocket maximum. Once you hit it, the plan covers the rest of your covered care for the year.

You cannot have both at the same time. Choosing Medicare Advantage means you are not using a Medigap policy, and if you have a Medigap policy already, you generally cannot use it alongside an Advantage plan.

Cost structure: lower premium versus lower exposure

This is where the two paths diverge most clearly.

Medicare Advantage plans often have low monthly premiums, and some in a given county have no separate premium beyond what you already pay for Part B. But that lower monthly cost usually comes with copays and coinsurance for each visit, procedure, or hospital stay, up to the plan's annual out-of-pocket maximum, which CMS sets a ceiling on each year but individual plans can set lower. If you have a light health care year, an Advantage plan can end up costing you very little. If you have a heavy year — a hospitalization, a new diagnosis, several specialist visits — you could pay meaningfully more before hitting that cap than you would with a Medigap policy.

Medigap policies work the other direction. The monthly premium is higher, sometimes considerably higher depending on the plan letter, your age, and your state. In exchange, most Medigap plans cover the large majority of what Original Medicare doesn't, so your costs per visit or per hospital stay are low or close to zero. You are paying more every month for predictability, rather than paying less every month and taking on more risk of a large bill in a bad year.

Neither structure is a mistake. It is a tradeoff between a lower fixed cost with variable exposure, and a higher fixed cost with very little exposure.

Network and provider freedom

Medicare Advantage plans generally require you to use their network, similar to how many employer health plans work. HMO-style Advantage plans usually require referrals to see specialists and offer no coverage for out-of-network care except emergencies. PPO-style Advantage plans allow out-of-network care but usually at a higher cost to you. Either way, the plan's provider directory matters, and directories change from year to year — a reason to check your plan's Annual Notice of Change every fall.

Original Medicare with a Medigap policy works differently. You can see any doctor or hospital in the country that accepts Medicare, without a network, without a referral, and largely without worrying whether a provider is "in" or "out." For people who split time between two states, travel frequently, or simply want the freedom to see any specialist without checking a directory first, this matters a great deal. It is also relevant if you have a doctor you have seen for years and do not want to risk losing access to if a network changes.

Side by side

When each tends to make more sense

Neither option is universally right, but the tradeoffs tend to line up with certain situations.

Medicare Advantage can make sense if you are comfortable with a defined network, want lower monthly costs while you are relatively healthy, and like the idea of extra benefits such as dental or vision bundled into one plan. It also tends to suit people who stay largely within one metro area or county and do not need nationwide provider access.

Original Medicare with a Medigap policy can make sense if you have ongoing health conditions that mean frequent doctor visits, if you travel often or split time between states, if you have specific specialists you are not willing to risk losing access to, or if predictable costs matter more to you than a lower premium. It's also worth understanding that Medigap medical underwriting outside your initial enrollment window can affect eligibility or price in many states, which is a detail worth walking through with someone who knows the rules in your state.

What doesn't change either way

A few things stay the same no matter which path you choose. You are still enrolled in Medicare Part A and Part B — Advantage and Medigap are both built on top of that base, not instead of it. You still pay your Part B premium regardless of which path you take. And you still need to think about drug coverage separately if you choose Original Medicare, since Medigap does not include a Part D drug plan the way most Advantage plans do.

The bottom line

Medicare Advantage and Original Medicare with a Medigap policy are two structurally different ways of covering the same core benefit, and the right one depends on your own health situation, how often you're on the road, which doctors you're not willing to give up, and whether you would rather pay a bit more every month for predictability or less every month with more risk in a bad year. Neither is the automatically smarter choice, no matter what an ad implies.

For the official rules on how Medicare Advantage and Medigap work, see Medicare.gov's guide to Medicare Advantage and Medicare.gov's guide to Medigap policies, as well as the Centers for Medicare & Medicaid Services.