When you become eligible for Medicare, one of the biggest choices is how to fill the gaps Original Medicare doesn't cover. The two main paths are Medicare Advantage and Medigap (also called Medicare Supplement Insurance). They work very differently, and the choice you make now can be hard to undo later.
This guide explains each option and gives you the questions to ask before you decide.
Note: Medicare rules, costs and plan availability change each year and vary by location. Confirm details for your area before enrolling.
A quick refresher: Original Medicare
Original Medicare has two parts:
- Part A — hospital insurance (inpatient stays, skilled nursing, hospice).
- Part B — medical insurance (doctor visits, outpatient care, preventive services).
Original Medicare pays a large share of covered costs, but not all of it. You still face deductibles and coinsurance, and there's no yearly cap on what you might pay. It also doesn't include most prescription drugs — that's Part D.
What Medicare Advantage is
Medicare Advantage (Part C) plans are offered by private insurers approved by Medicare. Instead of getting your benefits through Original Medicare, you get them through the plan.
How it typically works:
- Covers everything Part A and Part B cover.
- Often includes prescription drug coverage.
- May include extra benefits, such as some dental, vision or hearing coverage.
- Usually uses a network (often HMO or PPO).
- Has its own copays and coinsurance, and a yearly out-of-pocket limit.
Why people choose it: lower or no extra monthly premium in many areas, everything bundled into one plan, and a cap on yearly costs.
The trade-off: you generally need to use the plan's network, may need referrals or prior approval, and pay copays as you use care.
What Medigap is
Medigap policies are sold by private insurers and work alongside Original Medicare. Medicare pays first; your Medigap policy then helps pay your share — like deductibles and coinsurance.
How it typically works:
- Plans are standardized and identified by letters; the same letter has the same benefits from any insurer.
- You can generally see any doctor or hospital in the U.S. that accepts Medicare.
- No referrals needed.
- Doesn't include drug coverage — you'd add a separate Part D plan.
Why people choose it: freedom to see any provider that accepts Medicare, and predictable costs when you use care.
The trade-off: a monthly premium on top of your Part B premium, plus a separate Part D premium.
The timing issue most people don't hear about
In many states, there's a one-time window when you can buy any Medigap policy without health questions — generally around when you first enroll in Part B. Outside that window and other specific situations, insurers may be able to review your health history, charge more, or decline your application.
That means if you start with Medicare Advantage and later want to switch to Medigap, you may not be guaranteed a policy. Some states have their own protections. This is one of the most important things to understand before you choose.
Questions to ask before you pick
About your doctors
- Are my current doctors and hospitals in the Medicare Advantage plan's network?
- Do they accept Medicare patients (for Medigap)?
- Do I need specialists who might not be in a local network?
About your budget
- What's the total of premiums I'd pay each year under each option?
- What would I pay in a year with a lot of care — up to the Medicare Advantage out-of-pocket limit, versus Medigap plus Part D?
- Would I rather pay more upfront each month, or pay as I use care?
About your prescriptions
- Are all my medications on the plan's drug list?
- What tier are they on, and what will they cost?
About your lifestyle
- Do I travel often or spend part of the year in another state?
- How do I feel about referrals and prior authorization?
- Are extra benefits like dental or vision important to me?
About the future
- If my health changes, would I want the flexibility of Medigap?
- Would I be able to get a Medigap policy later in my state if I start with Medicare Advantage?
A simple way to think about it
- Medicare Advantage may suit you if you're comfortable with a network, want an all-in-one plan, and like lower upfront premiums.
- Medigap may suit you if you want to choose any provider that accepts Medicare, travel often, and prefer predictable costs in exchange for a higher monthly premium.
Neither is right for everyone.
How a licensed agent can help
An independent, licensed agent can compare Medicare Advantage and Medigap options available where you live, check your doctors and prescriptions, and explain the enrollment windows that apply to you.
Frequently asked questions
Can I have Medicare Advantage and Medigap at the same time?
No. Medigap only works with Original Medicare. If you join a Medicare Advantage plan, a Medigap policy can't pay toward your costs.
Does Medigap include prescription drug coverage?
Current Medigap policies don't include drug coverage. People who choose Medigap usually add a separate Medicare Part D plan.
Can I switch from Medicare Advantage to Medigap later?
You can usually change Medicare coverage during certain enrollment periods, but in many states a Medigap insurer can review your health and decline you or charge more outside your guaranteed-issue windows.