A Medicare Advantage plan (also called Part C) is a private insurance plan that replaces Original Medicare. The carrier becomes your primary insurance and you follow the plan's network and rules. A Medicare Supplement (also called Medigap) is a private policy that works alongside Original Medicare. Original Medicare pays first, and the supplement picks up most of what Medicare leaves behind. Both fill the same gap. They just fill it in opposite directions.
Most people turning 65 have to pick one or the other. You cannot use both at the same time. The decision matters because once you make a choice and your initial enrollment window closes, switching can become difficult depending on your health. Here is how to think about it without the sales pitch.
First, What Original Medicare Covers (and What It Does Not)
You cannot understand the supplement vs Advantage question without first understanding what Original Medicare actually pays for. Original Medicare is Part A (hospital) and Part B (doctor and outpatient). On its own it pays roughly 80% of approved costs, and there is no annual cap on what you can owe.
That 20% sounds small until you see a hospital bill. A $90,000 surgery leaves you on the hook for around $18,000 with Original Medicare alone. There is no maximum out-of-pocket. That is the gap both Medicare Advantage and Medicare Supplement are designed to fill.
Original Medicare also does not include prescription drug coverage, routine dental, routine vision, or hearing aids. Whichever path you go, you have to address those separately.
How Medicare Advantage Works
When you enroll in a Medicare Advantage plan, you are still technically enrolled in Medicare, but the private carrier takes over. You use the plan's ID card. You use the plan's network of doctors and hospitals. The plan decides what is covered and what needs prior authorization.
Most Medicare Advantage plans have a low monthly premium, often $0 to $50. In exchange, you pay copays and coinsurance when you use care. There is a maximum out-of-pocket each year, set by federal rules. In 2026 the in-network max is capped at $9,250, but most popular plans land somewhere between $4,000 and $8,000.
Most Medicare Advantage plans also bundle in a Part D drug plan and add extras like dental, vision, hearing, gym memberships, and over-the-counter benefit cards. The extras are real, but they are usually capped (for example, a $1,500 dental allowance per year).
How Medicare Supplement Works
A Medicare Supplement does not replace Medicare. Original Medicare stays your primary insurance. The supplement picks up the deductibles, copays, and coinsurance that Medicare leaves you owing.
The most popular plan today is Plan G. With Plan G, after you pay the small Part B deductible ($240 in 2025, indexed each year), the supplement covers essentially everything else Medicare approves. No copays at the doctor. No coinsurance at the hospital. You can see any doctor or specialist in the country who accepts Medicare. There is no network.
The trade-off is the monthly premium. Plan G usually runs $130 to $200 per month for someone turning 65 in most states, and rates increase with age. You also pay separately for a Part D drug plan (commonly $0 to $50 per month) and for dental or vision if you want it.
Side-by-Side Comparison
| Feature | Medicare Advantage | Medicare Supplement (Plan G) |
|---|---|---|
| Monthly premium | $0 -- $50 typical | $130 -- $200 typical at 65 |
| Network | HMO or PPO network | Any provider that accepts Medicare |
| Cost when you use care | Copays and coinsurance | Almost nothing after Part B deductible |
| Annual max out-of-pocket | $4,000 -- $9,250 (in-network) | Effectively the Part B deductible |
| Drug coverage | Usually included | Buy stand-alone Part D |
| Dental, vision, hearing | Limited extras built in | Buy separately if wanted |
| Prior authorizations | Common | Rare (Medicare rules apply) |
| Travel coverage | Usually in-network only (urgent/emergency out-of-network) | Any Medicare provider nationwide |
A Real Cost Example
Numbers tell the story better than features. Take a 65-year-old who has a fairly active year of healthcare: a few specialist visits, an outpatient procedure, and a short hospital stay.
- Medicare Advantage path: $25/month premium = $300 a year. Specialist copays, hospital copay, outpatient coinsurance, and procedure cost-share could easily add up to $3,500 to $5,000. Total annual cost: roughly $3,800 to $5,300.
- Medicare Supplement Plan G path: $160/month premium = $1,920 a year. Part D drug plan $25/month = $300 a year. Part B deductible = $240. Total annual cost: roughly $2,460. Almost nothing else owed for the year.
In a heavy-use year the supplement is usually cheaper. In a light-use year (one or two doctor visits, no procedures), the Medicare Advantage plan is usually cheaper. The right answer is the path that lines up with the year you are most worried about.
When Medicare Advantage Is the Right Fit
Medicare Advantage is not a worse product. It is a different product. It tends to fit best when:
- 1. Budget is tight. A $0 or low-premium plan keeps your fixed monthly cost down. If you are healthy and rarely use care, the math can work in your favor.
- 2. You stay close to home. If you live in one area and your doctors are in the local network, network restrictions do not affect your day-to-day life.
- 3. You like the extra benefits. Dental, vision, and hearing benefits, plus over-the-counter cards and gym memberships, can be meaningful for some people.
- 4. You want one ID card. Drugs, medical, and extras all rolled into one plan can be simpler to manage.
When Medicare Supplement Is the Right Fit
Medicare Supplement tends to fit best when:
- 1. You want predictability. You pay a higher premium, but you almost never get a surprise medical bill. Some people sleep better knowing the cost is fixed.
- 2. You travel or split time between states. The supplement works with any provider in the country that accepts Medicare. No network. No referrals.
- 3. You see a lot of specialists or have ongoing conditions. Heavy users of care almost always come out ahead on a supplement because the plan eliminates the copays and coinsurance that pile up.
- 4. You have specific doctors you want to keep. Almost every doctor in the country accepts Medicare, which means a supplement preserves your existing relationships.
- 5. You want to avoid prior authorizations. Original Medicare and your supplement do not require the prior auth process that Medicare Advantage plans often run on procedures, scans, and durable medical equipment.
The Switching Window Most People Miss
Here is the part that catches families off guard. You can change Medicare Advantage plans every year during the Annual Enrollment Period (October 15 to December 7). That part is easy.
Switching from Medicare Advantage to a Medicare Supplement is a different story. After your first 6 months of being on Part B, supplement carriers can ask you health questions. If you have certain conditions, they can decline you. That is called underwriting.
A few states (like New York, Connecticut, and Massachusetts) have year-round guaranteed issue rules for supplements. Most states do not. So in most of the country, your healthiest moment to make this choice is when you first turn 65, because you have guaranteed acceptance into any supplement with no medical questions.
That is why this decision is worth getting right the first time. Picking a Medicare Advantage plan at 65 because the premium is low, then trying to move to a supplement at 72 after a heart issue, can mean you cannot move at all.
How to Decide: A 5-Step Walkthrough
- 1. List your doctors. Write down your primary care doctor and any specialists you want to keep. With a supplement, you keep them as long as they accept Medicare. With Medicare Advantage, you check the network.
- 2. List your prescriptions. Names and dosages. Drug coverage works differently in each path, and the right plan can save you thousands per year on the same medications.
- 3. Look at your travel. If you spend time in another state, visit grandkids out of state, or are a snowbird, that pushes you toward a supplement.
- 4. Run a worst-case year. Ask yourself: if I had a heart attack or a cancer diagnosis next year, what would each plan actually cost me? Compare the worst-case bills, not the best-case bills.
- 5. Get rates from multiple carriers. Supplement premiums for the same Plan G vary widely between carriers. The benefits are identical because the plan letter is standardized. Cheaper is just cheaper.
A Couple of Things Most People Get Wrong
A few patterns I see on calls almost every week:
- Picking based on premium alone. A $0 premium plan is not free. The cost shows up when you use care. Compare total annual cost, not the sticker.
- Assuming all Plan G policies are different. They are not. Plan G is standardized by federal law. Aetna's Plan G covers exactly what Mutual of Omaha's Plan G covers. Only the price and the carrier service differ.
- Trusting the TV commercial. The flashy ads are usually for Medicare Advantage plans because the carriers spend big marketing dollars to recruit. That does not mean those plans are wrong, it just means TV advertising is not analysis.
- Skipping Part D when on a supplement. A supplement does not include drugs. Skipping Part D when you sign up triggers a permanent late enrollment penalty later. Always pair the supplement with a Part D plan from day one.
Frequently Asked Questions
What is the main difference between Medicare Advantage and Medicare Supplement?
Medicare Advantage replaces Original Medicare. The plan becomes your primary insurance and you use the plan's network and rules. Medicare Supplement works alongside Original Medicare. Original Medicare pays first and the supplement picks up most or all of what Medicare leaves you owing.
Which costs more, Medicare Advantage or Medicare Supplement?
Medicare Advantage usually has a lower monthly premium, often $0 to $50, but you pay copays and coinsurance every time you use care, with a max out-of-pocket that can run $4,000 to $8,000 per year. Medicare Supplement Plan G runs about $130 to $200 per month in most states for someone turning 65, plus the Part D drug plan, but you pay almost nothing when you use care.
Can I switch from Medicare Advantage to Medicare Supplement later?
You can apply, but outside of your initial Medigap open enrollment window the supplement carrier can underwrite you and decline coverage based on your health. The safest time to choose between them is when you first turn 65, because that is when you have guaranteed acceptance into a supplement with no medical questions.
Do Medicare Advantage plans cover dental, vision, and prescriptions?
Most Medicare Advantage plans bundle in a Part D drug plan and add some dental, vision, and hearing benefits. The amounts and limits vary by plan. A Medicare Supplement does not include drug coverage, dental, vision, or hearing, so you buy a stand-alone Part D drug plan and add dental or vision separately if you want it.
Which is better for someone in good health?
There is no universal answer. People who travel often, want to see any doctor that accepts Medicare, or are worried about a future health event tend to like Medicare Supplement because of the predictable cost and freedom. People who want a low monthly premium and are comfortable with a network often like Medicare Advantage. The right choice depends on your doctors, your prescriptions, your travel, and your budget.
That is what I do at Chiasson Consulting. I sit down with you, look at your doctors, your prescriptions, and your budget, then put the actual numbers from multiple carriers in front of you so you can pick the one that fits. The consultation is free.
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