The Core Difference
Medicare Advantage (Part C) replaces Original Medicare entirely with a private plan, often at a lower premium with extra benefits but network restrictions. A Medicare Supplement (Medigap) plan works alongside Original Medicare, paying some or all of its deductibles and coinsurance — you keep Original Medicare's nationwide provider access, but pay a separate Medigap premium. You cannot have both at the same time; it's one or the other.
Side-by-Side Comparison
| Medicare Advantage | Medigap (Supplement) | |
|---|---|---|
| Monthly premium | Often $0–$50/mo | $100–$300+/mo depending on plan letter |
| Provider network | HMO/PPO network restrictions | Any provider nationwide that accepts Medicare |
| Extra benefits | Often includes dental, vision, hearing | None — covers only Original Medicare's gaps |
| Drug coverage | Usually bundled in (Part D included) | Requires separate standalone Part D plan |
| Out-of-pocket predictability | Annual out-of-pocket max, but copays/coinsurance vary by service | Very predictable — most plans cover nearly all cost-sharing |
When Medicare Advantage Makes Sense
If you want lower monthly costs, extra benefits like dental and vision, and don't mind a defined provider network, Medicare Advantage is usually the more budget-friendly choice — especially for people in good health who don't anticipate needing extensive specialist care outside a network.
When Medigap Makes Sense
If you want the freedom to see any provider nationwide that accepts Medicare, predictable out-of-pocket costs, and you're willing to pay a higher monthly premium for that flexibility, Medigap is usually the better fit — particularly for people who travel frequently or have complex ongoing health needs.
The Timing Trap to Avoid
Your best opportunity to buy a Medigap policy without medical underwriting is the 6-month window starting when you turn 65 and enroll in Part B. If you choose Medicare Advantage first and later want to switch to Medigap, insurers in most states can medically underwrite you — potentially charging more or denying coverage based on your health. Think through this choice carefully before your Initial Enrollment Period ends.
Frequently Asked Questions
Yes, but outside your initial guaranteed-issue window, insurers in most states can medically underwrite the application, meaning you could be charged more or denied based on health conditions.
No — Medigap plans sold today don't include drug coverage. You need a separate standalone Part D plan if you choose Original Medicare plus Medigap.
Medicare Advantage enrollment has grown to cover more than half of all Medicare beneficiaries nationally, largely due to its lower premiums and bundled extra benefits.