The Core Difference: How Each Plan Works

Medicare Advantage (Part C) is an all-in-one plan run by a private insurance company. It includes hospital, doctor, and prescription drug coverage in one policy. You pay a monthly premium, and the insurance company handles most of your claims. You must use doctors and hospitals in the plan's network, except in emergencies.

Medigap (also called Supplement Insurance) is a separate policy sold by private insurers that works alongside Original Medicare (Parts A and B). It covers costs that Medicare itself does not pay — copayments, coinsurance, and deductibles. You keep your Original Medicare coverage and add Medigap on top of it. You can see any doctor or hospital that accepts Medicare, anywhere in the country.

The choice between them depends on how you use healthcare, what you can afford upfront, and whether you want flexibility or simplicity. Neither is universally "best" — the right plan depends on your specific situation.

Key Takeaways

  • Medicare Advantage locks you into a network of doctors and hospitals, but typically has lower monthly premiums and includes prescription drug coverage built in.
  • Medigap lets you see any Medicare-accepting doctor anywhere, but costs more in monthly premiums and does not cover prescription drugs — you need Part D for that.
  • Medicare Advantage plans cap your out-of-pocket costs each year; Medigap plans do not, though Medigap holders usually spend less overall if they see doctors frequently.
  • Switching between the two is possible but restricted to certain times of year, and some people cannot switch if they have pre-existing conditions under certain circumstances.
  • Your choice should reflect whether you have established doctors you want to keep, how often you expect to need care, and whether you prefer predictable costs or maximum flexibility.

Medicare Advantage: Lower Premiums, Restricted Networks

Medicare Advantage plans appeal to people who want simplicity and low monthly costs. Most plans charge zero or a small monthly premium on top of your Part B premium. They bundle hospital, doctor, and drug coverage into one bill, so you do not have to manage multiple policies.

The trade-off is the network. You must use doctors and hospitals the plan contracts with, except in emergencies or urgent care situations. If your longtime cardiologist is not in the plan's network, you either switch doctors or pay out-of-network rates. Plans vary widely — some have broad networks, others are narrow. You need to check whether your current doctors participate before you enroll.

Medicare Advantage plans also cap your out-of-pocket costs. Once you hit the annual limit (which varies by plan but is set by Medicare), the plan pays 100 percent of covered services for the rest of that year. This ceiling provides predictability if you expect significant medical expenses.

Most Medicare Advantage plans include prescription drug coverage (Part D), so you do not buy it separately. Some plans also cover dental, vision, or hearing aids — benefits Original Medicare does not cover. However, these extras vary widely by plan and by region.

Medigap: Flexibility and Predictability, Higher Premiums

Medigap appeals to people who have established relationships with specific doctors, travel frequently, or want to avoid network restrictions. Because you keep Original Medicare, you can see any doctor or hospital that accepts Medicare, in any state. There is no referral requirement and no prior authorization for most services.

Medigap plans are standardized by the federal government. There are ten different plan types (A, B, D, G, K, L, M, N, and two others), and each one covers the same set of costs regardless of which insurance company sells it. Plan G, for example, covers the Part B deductible and coinsurance at every company that offers it. This standardization makes it straightforward to compare prices across insurers.

The downside is cost. Medigap premiums are typically higher than Medicare Advantage premiums — often $100 to $300 per month depending on the plan type and your age. You also must buy Part D separately for prescription drug coverage; Medigap does not include it. And Medigap plans do not cap your out-of-pocket costs the way Medicare Advantage does, though in practice most Medigap holders spend less overall because they have fewer copayments and coinsurance.

Medigap premiums can increase with age or when you renew, depending on the pricing method your state allows. Some states use "attained age" pricing (your premium rises as you get older), others use "issue age" pricing (your premium is locked to the age you bought the plan), and some allow both.

Comparing Costs: What You Actually Pay

Cost comparison is not straightforward because the two plan types charge you in different ways. Medicare Advantage has a low or zero monthly premium but charges copayments and coinsurance when you use services. Medigap has a higher monthly premium but lower or zero copayments.

If you rarely see a doctor, Medicare Advantage is usually cheaper. You pay the low premium and little else. If you see doctors frequently or have chronic conditions requiring ongoing care, Medigap often costs less overall because you avoid copayments and coinsurance at each visit.

The break-even point depends on your specific plan, your doctors' fees, and how much care you need. Someone with diabetes, heart disease, or arthritis who sees multiple specialists typically saves money with Medigap. Someone who sees a doctor once a year typically saves with Medicare Advantage.

You should request a detailed cost estimate from plans you are considering. Ask: What is the monthly premium? What are the copayments for a doctor visit, a specialist visit, and a hospital stay? What is the annual out-of-pocket maximum? Then estimate your own usage based on your health and habits.

Prescription Drug Coverage: Part D and Plan Differences

Most Medicare Advantage plans include prescription drug coverage. The plan decides which drugs it covers, at what cost tier, and which pharmacies you can use. If your regular medication is not on the plan's formulary, you may need to switch drugs or pay more.

Medigap does not include drug coverage. You must buy Part D separately from a standalone prescription drug plan. You choose your own Part D plan based on which drugs you take and which pharmacies you prefer. Part D plans are not standardized the way Medigap plans are, so you need to compare them each year.

If you take expensive medications or multiple drugs, check the formulary of any Medicare Advantage plan before you enroll. A plan with a low premium might charge high copayments for your specific drugs, making it more expensive overall.

When You Can Switch Between Plan Types

You cannot switch from Medicare Advantage to Medigap (or vice versa) whenever you want. The federal government restricts switching to specific enrollment periods.

If you are newly may be able to access for Medicare, you have a six-month window called the Medigap Open Enrollment Period. During this time, you can buy any Medigap plan without medical underwriting, regardless of pre-existing conditions. This window is the best time to switch if you think you might want Medigap later.

Outside this window, switching to Medigap may require you to answer health questions, and insurers can deny coverage or charge more based on your health history. Some states have additional protections, but not all.

You can switch Medicare Advantage plans during the Annual Enrollment Period (October 15 to December 7 each year) or during the Medicare Advantage Open Enrollment Period (January 1 to March 31). You can also switch if you move out of your plan's service area or if you lose coverage.

Which Plan Type Matches Your Situation

Choose Medicare Advantage if: you are comfortable with a network of doctors, you do not have established relationships with specialists outside that network, you expect moderate healthcare use, you want lower monthly premiums, or you value dental or vision coverage.

Choose Medigap if: you have specific doctors you want to keep seeing, you travel frequently or split time between states, you have chronic conditions requiring ongoing specialist care, you want maximum flexibility in where you receive care, or you prefer predictable copayments.

If you are unsure, ask yourself: Do I have doctors I am committed to keeping? How often do I see a doctor in a typical year? Do I take expensive medications? Am I willing to switch doctors if necessary? Your answers will point toward one plan type or the other.

Frequently Asked Questions

Can I switch from Medicare Advantage to Medigap if I change my mind?

You can switch during the Annual Enrollment Period (October 15 to December 7) without restrictions. Outside that window, you may face medical underwriting, meaning the insurance company can deny you or charge more based on your health. Your best protection is to use your Medigap Open Enrollment Period (the first six months you have Part B) to buy Medigap if you think you might want it later.

Do I need Part D if I have Medicare Advantage?

Most Medicare Advantage plans include prescription drug coverage, so you do not need a separate Part D plan. However, check your specific plan's formulary to confirm it covers your medications. If you have Medigap, you must buy Part D separately.

What happens if my doctor leaves my Medicare Advantage plan's network?

You have the right to continue seeing that doctor for a limited time (usually 30 to 90 days) while you find a new in-network doctor. If you cannot find an acceptable replacement, you may be able to switch plans outside the normal enrollment period. Contact your plan when ready if this happens.

Is Medigap more expensive than Medicare Advantage?

Medigap premiums are usually higher, but total costs depend on how much healthcare you use. If you see doctors frequently, Medigap often costs less overall because you avoid copayments. If you rarely see a doctor, Medicare Advantage is usually cheaper. Request cost estimates from specific plans to compare.

Can I have both Medicare Advantage and Medigap at the same time?

No. You can have either Original Medicare with Medigap, or Medicare Advantage. You cannot have both simultaneously. If you switch from one to the other, your previous coverage ends.