When you become eligible for Medicare, you face one of the most important healthcare decisions you'll make: should you choose Medicare Advantage (Part C) or keep Original Medicare and add a Medigap supplement? These two paths work completely differently — and choosing the wrong one can cost you significantly or limit your access to doctors and specialists.
How Each System Works
Original Medicare + Medigap
Original Medicare (Parts A and B) is the federal health insurance program. Medicare pays 80% of most covered outpatient services; you pay the remaining 20% (your coinsurance), plus deductibles and copays. A Medicare Supplement (Medigap) plan from a private insurer pays some or all of your share, depending on which plan letter you choose.
With this combination, you can see any doctor or hospital in the US that accepts Medicare — no network restrictions, no referrals needed. Your out-of-pocket exposure is highly predictable. You'll also need a separate Part D plan for prescription drug coverage.
Medicare Advantage (Part C)
Medicare Advantage is an alternative to Original Medicare. A private insurance company contracts with Medicare to deliver your Part A, Part B, and usually Part D benefits in a single plan. You still pay your Medicare Part B premium, plus any plan premium the insurer charges (often $0 in many markets).
The trade-off: Medicare Advantage plans have networks (HMO or PPO), prior authorization requirements, and cost-sharing structures (copays, deductibles, annual out-of-pocket maximums) that vary by plan. You generally must use in-network providers, and the plan controls access to specialists.
Side-by-Side Comparison
| Factor | Original Medicare + Medigap | Medicare Advantage |
|---|---|---|
| Doctor choice | Any doctor who accepts Medicare — no network | In-network only (HMO) or higher cost out-of-network (PPO) |
| Monthly premium | Part B premium + Medigap premium ($100–$280/mo for Plan G) | Part B premium + $0–$50/mo plan premium (often $0) |
| Out-of-pocket costs | Very predictable — Plan G: only $257 Part B deductible/yr | Variable — copays per visit; annual OOP maximum can be $3,000–$8,300 |
| Prescription drugs | Separate Part D plan required | Usually included (MAPD plans) |
| Extra benefits | None (dental, vision, hearing not covered) | Often includes dental, vision, hearing, fitness, PERS |
| Prior authorization | Not required for most services | Required for many specialist visits, procedures, hospitalizations |
| Travel coverage | Any Medicare provider nationwide; Medigap covers foreign travel emergency | Emergency/urgent care nationwide; routine out-of-network usually not covered |
| Cancer/complex care | Access to any Medicare-participating specialist anywhere in the US | Restricted to plan network; out-of-network cancer centers may not be covered |
Who Benefits Most from Each Option
Medicare Advantage Is Often Better If You…
- Are generally healthy and use healthcare infrequently
- Want low or $0 monthly premiums and can accept variable out-of-pocket costs
- Live in an area with a robust Medicare Advantage network that includes your doctors
- Want extra benefits like dental, vision, and hearing through one plan
- Are comfortable with plan administration (prior authorizations, network management)
Medigap (Supplement) Is Often Better If You…
- Have chronic conditions or see multiple specialists regularly
- Want to see any doctor who accepts Medicare — including specialists at major medical centers
- Travel frequently or split time between states
- Prefer predictable, fixed healthcare costs regardless of how much care you use
- Want to avoid prior authorization delays for medical procedures
- Have been diagnosed with — or have a family history of — cancer, heart disease, or other serious conditions
The Real Cost Comparison
The "Medicare Advantage is cheaper" claim requires examination. Consider a 65-year-old in a typical market:
| Scenario | Medigap Plan G Annual Cost | Medicare Advantage Annual Cost |
|---|---|---|
| Healthy year (few visits) | ~$2,100 (premium) + $257 deductible = ~$2,357 | $0 premium + ~$200–$500 in copays = ~$200–$500 |
| Moderate use (specialist + surgery) | ~$2,100 (premium) + $257 deductible = ~$2,357 (covered) | $0 premium + copays + coinsurance = $2,000–$4,000 |
| Major illness (hospitalization) | ~$2,100 (premium) + $257 deductible = ~$2,357 (fully covered) | $0 premium + cost-sharing up to $8,300 OOP maximum |
Estimates using typical 2026 Plan G premium for a 65-year-old and a typical Medicare Advantage plan with $0 premium. Actual costs vary significantly by plan, insurer, and location.
The Decision You Can't Easily Undo
This is the most important consideration in choosing between the two options.
If you start with Medigap and want to switch to Medicare Advantage, you can do so during the Annual Enrollment Period (Oct 15 – Dec 7) with no health questions.
But if you start with Medicare Advantage and later want Medigap, you will likely face medical underwriting — and could be denied coverage or charged more based on your health conditions. The exceptions (birthday rules, trial rights, guaranteed issue states) are limited. Many people who develop serious health conditions while enrolled in Advantage find themselves unable to switch to Medigap when they need it most.
This asymmetry leads many experts to recommend that seniors who can afford Medigap premiums start with Medigap — especially if they have any existing health conditions.
Frequently Asked Questions
What is the main difference between Medicare Advantage and Medigap?
Medicare Advantage (Part C) replaces Original Medicare with a private plan — your coverage depends on the plan's network, formulary, and benefits. Medigap supplements Original Medicare — you keep Medicare Parts A and B and the Medigap plan pays cost-sharing. With Medigap, you can see any doctor who accepts Medicare nationwide, with no network restrictions.
Is Medicare Advantage or Medigap more expensive?
It depends. Medicare Advantage plans often have $0 or very low monthly premiums, which looks attractive upfront. However, Advantage plans have copays, deductibles, and out-of-pocket maximums that can add up significantly if you use a lot of healthcare. Medigap (especially Plan G) has higher monthly premiums but minimal out-of-pocket costs after the Part B deductible. For healthy seniors with low medical use, Advantage may cost less. For those with chronic conditions or frequent healthcare use, Medigap often provides more predictable total costs.
Can I switch from Medicare Advantage to Medigap?
You can switch from Medicare Advantage back to Original Medicare during the Medicare Advantage Open Enrollment Period (January 1 – March 31) or Annual Enrollment Period (October 15 – December 7). However, once you switch back to Original Medicare, you typically need to pass medical underwriting to enroll in a Medigap plan (exceptions: CA, FL, OR birthday rules; NY/NJ year-round guaranteed issue; and your trial right period if within 12 months of first enrolling in Medicare Advantage).
Do Medicare Advantage plans cover more than Original Medicare?
Medicare Advantage plans must cover everything Original Medicare covers, but they often add benefits like dental, vision, hearing, fitness memberships, and sometimes personal emergency response systems (PERS). However, these extra benefits must be weighed against network restrictions, prior authorization requirements, and the potential for higher cost-sharing if you get seriously ill.
Can I have both Medicare Advantage and a Medigap plan?
No. It is illegal to sell someone a Medigap policy if they are enrolled in a Medicare Advantage plan, and Medigap does not work with Medicare Advantage. You must choose one path: either Original Medicare + Medigap (+ Part D), or Medicare Advantage (which usually includes drug coverage).
This site provides general information about Medicare Supplement insurance and medical alert devices. It is not affiliated with or endorsed by the Centers for Medicare & Medicaid Services (CMS) or any government agency. This is not medical or insurance advice. Always consult a licensed insurance professional for personalized guidance.
Medicare rules, premiums, and plan availability change annually. Always verify current information with Medicare.gov, your State Insurance Department, or a licensed insurance advisor. For free, unbiased help, contact your State Health Insurance Assistance Program (SHIP) at shiphelp.org.
Sources
- Medicare.gov. How does Medicare Advantage work? medicare.gov. Retrieved June 2026.
- CMS. Choosing a Medigap Policy. Publication 02110. cms.gov. Retrieved June 2026.
- KFF. Medicare Advantage 2026 Spotlight. kff.org. Retrieved June 2026.