How Medicare Advantage works
Medicare Advantage is also called Part C. When you enroll in a Medicare Advantage plan, you still have Medicare — you continue paying your Part B premium and any applicable IRMAA — but Medicare contracts with a private insurance company to deliver your Part A and Part B benefits through that plan. Most Medicare Advantage plans also include Part D prescription drug coverage; some include extras that vary by plan and service area.
Because Medicare Advantage plans are administered by private companies, they typically use provider networks. You generally must use in-network providers to keep cost-sharing at its lower in-network levels. Plans use different network types — HMOs require referrals to see specialists and limit out-of-network access; PPOs allow out-of-network access with higher cost-sharing; PFFS and SNP plans have their own structures. Plan availability and network composition vary by county.
Cost-sharing under Medicare Advantage is plan-specific. Each plan sets its own copays for visits, hospital stays, and other services, plus an annual maximum out-of-pocket limit that caps your total exposure for Medicare-covered services in a year.
How Medigap works
Medigap, also called Medicare Supplement Insurance, works alongside Original Medicare. Original Medicare pays its share of covered services first; Medigap pays some or all of the deductibles, coinsurance, and copayments that Original Medicare leaves to you. There is no provider network on a Medigap policy itself — if a provider accepts Medicare, they accept Medigap.
Medigap policies are standardized in most states. Plans are labeled with letters (Plan G, Plan N, Plan F for those who qualify, etc.), and the same letter from any company must cover the same services. The standardization makes comparing plans across companies straightforward — same benefits, different premium and company financial strength.
A standalone Part D prescription drug plan is typically added to Original Medicare with Medigap, since Medigap policies sold today do not include drug coverage.
Key differences
Provider access
Original Medicare with Medigap gives broad provider access — any U.S. provider who accepts Medicare. Medicare Advantage typically limits you to a network for full coverage. If you travel often, see specialists in multiple states, or want maximum flexibility, the Original Medicare path tends to be more accommodating.
Cost predictability
Medigap shifts most cost-sharing into a level monthly premium. After the premium and any small remaining cost-sharing under the chosen plan letter, your annual out-of-pocket exposure for Medicare-covered services is fairly predictable. Medicare Advantage typically has lower premiums but variable cost-sharing — light usage means low total cost; heavy usage approaches the plan's annual maximum out-of-pocket limit.
Bundled drug coverage
Medicare Advantage plans typically include Part D prescription drug coverage. With Original Medicare and Medigap, you add a standalone Part D plan separately. The standalone plan can be selected based on your specific medications and pharmacy preferences.
Extras and additional benefits
Medicare Advantage plans may include benefits beyond Original Medicare, with specific offerings varying by plan and area. Medigap policies do not include these extras — Medigap focuses strictly on filling Original Medicare cost-sharing gaps.
When each tends to fit
The right choice is personal and depends on your circumstances. The factors below are common considerations, not universal rules.
People who often consider Original Medicare with Medigap tend to value broad provider access, travel between states regularly, prefer predictable monthly costs even at higher premium, and are willing to manage a separate Part D plan.
People who often consider Medicare Advantage tend to be comfortable with provider networks, value lower monthly premium, want bundled drug coverage and additional benefits, and live in an area where the plan's network includes their preferred providers.
The Medigap enrollment window matters
Medigap has a one-time guaranteed-issue period: the six months starting when you first enroll in Part B at age 65 or later. During this window, insurance companies cannot deny you coverage or charge more based on your health. Outside this window, in most states, companies can use medical underwriting and may decline applicants or charge more.
This matters for the long-term flexibility of switching between paths. If you choose Medicare Advantage at 65 and later want to move to Original Medicare with Medigap, you may face medical underwriting depending on state and timing. Some states have additional Medigap consumer protections; check your state's rules.
Switching between paths
You can switch from Medicare Advantage back to Original Medicare during the Annual Enrollment Period (October 15 through December 7) or the Medicare Advantage Open Enrollment Period (January 1 through March 31). Adding a Medigap policy after your initial guaranteed-issue window may involve underwriting in most states.
You can switch from Original Medicare to Medicare Advantage during AEP. There is no underwriting to enroll in a Medicare Advantage plan as long as you are eligible and live in the plan's service area.
How to decide
The decision is rarely about which path is generically better — both are legitimate options used by millions of people. It is about which path fits your situation: where you live, where you travel, what providers you want, what kind of cost predictability you value, and what budget works for you.
A licensed independent advisor can walk through both paths with you, model expected total annual cost based on your specific medications and likely usage, and help you identify which path is more accommodating for your needs. The decision deserves time and a real comparison — not a quick choice driven by a single feature or premium.
FAQ
Frequently asked
Continue learning