Medicare Advantage vs. Medigap: The Real Tradeoffs, Side by Side For 2027

The basic structural difference

Medicare Advantage (Part C) replaces Original Medicare with a private plan that bundles Parts A and B, usually Part D drug coverage too, plus extra benefits like dental, vision, and hearing. Medigap (Medicare Supplement) works differently: it doesn't replace Original Medicare, it pays alongside it, covering cost-sharing gaps like deductibles, copays, and coinsurance that Original Medicare leaves you responsible for. Medigap plans are standardized by letter (A through N), so a Plan G from one insurer covers the exact same core benefits as a Plan G from any other insurer — only the premium differs.

This standardization is genuinely useful when comparison shopping, since it removes one layer of complexity entirely: you're never comparing different benefit packages under the same plan letter, only different premiums and customer service reputations across insurers offering the identical Plan G, for instance. Medicare Advantage plans, by contrast, vary considerably from one carrier and one county to the next, since each private insurer designs its own specific network, formulary, and extra benefit package within CMS's broader rules.

Cost: premiums vs. out-of-pocket exposure

Medicare Advantage typically wins on upfront monthly cost: the average premium dropped to roughly $14 a month in 2026, and most enrollees are in plans with a $0 premium beyond the standard Part B premium. But Original Medicare has no annual out-of-pocket maximum on its own, which is exactly why Medicare Advantage plans are required to include one — up to $9,250 for in-network care in 2026, though individual plans often set it lower. Medigap flips this entirely: you pay a meaningfully higher monthly premium, plus a separate Part D plan for drug coverage, but your actual out-of-pocket costs stay far more predictable regardless of how much care you need in a given year.

According to KFF research, the average in-network out-of-pocket limit actually built into Medicare Advantage plans runs closer to $5,421, notably below the CMS-permitted maximum, though PPO plans that also cover out-of-network care combine to an average closer to $9,825 when both figures are counted together. This distinction between the CMS-permitted ceiling and each plan's actual chosen limit matters enormously when comparing specific plans side by side, since two plans both technically compliant with CMS rules can still expose you to meaningfully different worst-case costs.

Access: networks and prior authorization vs. total freedom

Medicare Advantage plans generally use provider networks, similar to HMO or PPO structures in commercial insurance, and commonly require prior authorization before covering many services. Under Original Medicare paired with Medigap, there are no networks at all — you can see any provider nationwide who accepts Medicare, with no referrals and no pre-approval process, since Medicare itself, not a private insurer, determines whether a given service is covered at all.

This distinction matters most in practice for two groups of people: those who split time between two states or travel frequently, since a Medicare Advantage network typically operates within a specific service area, and those who have an established relationship with a specialist or facility who may or may not be included in a given plan's network in any specific year. Because Medicare Advantage networks can and do change between plan years, even staying enrolled in the exact same plan doesn't guarantee your specific providers remain in-network going forward.

The underwriting trap most people don't know about

This is the detail that catches the most people off guard, and it's rarely explained clearly at the point of enrollment: if you choose Medicare Advantage first and later decide you want to switch to Medigap, most states allow insurers to medically underwrite you at that point. That means an insurer can charge you significantly more, or deny you coverage entirely, based on health conditions you've developed since turning 65. Choosing Medicare Advantage isn't necessarily permanent, but switching away from it later is far less straightforward than switching into it in the first place.

The asymmetry here is worth sitting with for a moment: moving from Medigap into Medicare Advantage carries essentially no underwriting risk, since you can generally switch during any Annual Enrollment Period without a health questionnaire. Moving the other direction, from Medicare Advantage back to Medigap, is where the real risk concentrates. This asymmetry is precisely why the decision at 65 carries more long-term weight than a simple cost comparison alone would suggest.

When guaranteed-issue protections do apply

• The initial Medigap Open Enrollment Period: the 6 months starting when you turn 65 and enroll in Part B, during which insurers cannot deny you or charge more based on health.
• If your Medicare Advantage plan is discontinued or non-renewed by the carrier, you generally gain a guaranteed-issue right to purchase a Medigap policy.
• Certain state-specific rules that extend guaranteed-issue rights beyond the federal minimum, covered in more detail below.

Outside of these specific windows, medical underwriting is the default in most states, which is exactly why the timing of this decision carries more long-term weight than it might initially appear to.

State variation: some places are safer than others

A number of states have adopted their own additional consumer protections beyond the federal baseline. Fifteen states currently offer an annual "birthday rule" window allowing Medigap policyholders to switch plans without medical underwriting, with New Mexico set to join in 2027. A smaller number of states, including New York, go further and require year-round guaranteed issue with community rating, meaning insurers there must accept Medigap applicants at any time regardless of health status, and can't charge more for pre-existing conditions. These stronger state protections meaningfully reduce the underwriting trap described above, but they remain the exception rather than the rule across the country overall.

If you live in one of these stronger-protection states, the underwriting trap discussed earlier applies to you far less than it does nationally, and you may have considerably more flexibility to move between Medicare Advantage and Medigap over time without facing the same financial risk. If you're not sure whether your own state offers any of these additional protections, this is exactly the kind of detail worth confirming directly with a licensed agent or your state insurance department before making a decision you assume is easily reversible later on.

Making the actual decision at 65

A single difficult health year usually doesn't flip the math decisively in Medigap's favor on its own — what tends to matter more is a longer-term trajectory. Medigap's cost stays essentially flat regardless of how much care you use, while Medicare Advantage out-of-pocket costs rise specifically in the years you need more care. If you're generally healthy, budget-conscious, and comfortable with network restrictions, Medicare Advantage often makes sense. If predictable costs, unrestricted provider access, and long-term flexibility matter more to you than the lower starting premium, Medigap, paired with a standalone Part D plan, is often the stronger fit — particularly since the guaranteed-issue window to make that choice easily is time-limited and does not typically reopen later on.

Common questions about Medicare Advantage vs. Medigap

Have a question that isn't answered below? Our full Medicare FAQ hub covers broader eligibility, enrollment, and cost questions.