- The core difference between Medicare Advantage (Part C) and Medicare Supplement (Medigap)
- How each plan actually pays your medical bills — and what you owe out of pocket
- A side-by-side cost and coverage comparison using 2026 figures
- Who is better served by each type of plan, and why
- The enrollment timing mistake that can lock you out of Medigap permanently
- Answers to the questions clients ask most before choosing a plan
Start Here: What Is the Difference?
When you turn 65 and enroll in Medicare, you get Original Medicare — Part A (hospital) and Part B (medical). Original Medicare is solid coverage, but it does not pay for everything. It leaves you responsible for deductibles, copays, and coinsurance with no annual cap on what you can owe.
That is where private insurance comes in. You have two primary ways to fill that gap:
- Medicare Advantage (Part C) — a private plan that replaces your Original Medicare entirely.
- Medicare Supplement, or Medigap — a private policy that works alongside Original Medicare and covers what it leaves unpaid.
These are not two versions of the same thing. They work in completely different ways. Understanding that distinction is the most important step before making a Medicare decision.
How Medicare Advantage Works
A Medicare Advantage plan is sold by a private insurance company approved by Medicare. When you enroll, that company takes over your coverage completely. Instead of Original Medicare paying your doctors and hospitals, your Advantage plan does.
Most MA plans are structured like an HMO or PPO. That means you typically have a network of doctors you need to use, and you may need a referral to see a specialist. Many plans bundle dental, vision, hearing, and prescription drug coverage into one card, and most charge $0 in additional monthly premiums beyond your standard Part B premium.
The tradeoff is that you pay copays and coinsurance each time you use care. In 2026, the annual out-of-pocket maximum for in-network care can be as high as $9,350.
Key point: Medicare Advantage replaces Medicare.Your original Medicare card goes to the back of your wallet. You use your Advantage plan's card. Your doctors and hospitals must be in that plan's network for full benefits. Seeing an out-of-network provider can result in significantly higher costs.
How Medicare Supplement Works
A Medicare Supplement plan works differently. Your Original Medicare stays active and pays first. Then your Medigap policy picks up some or all of what Medicare leaves unpaid — copays, coinsurance, and deductibles.
Because you are still on Original Medicare, you can see any doctor or specialist in the country who accepts Medicare. No networks. No referrals. No prior authorizations for most services. Plan G is the most popular option in 2026 and covers nearly everything except the Part B deductible, which is $283 this year.
The tradeoff is a higher monthly premium. Depending on age, health history, and state, Plan G premiums typically run between $130–$200 per month on top of your Part B premium. You also need a separate Part D plan for prescription drugs.
Key point: Medicare Supplement works alongside Medicare.You keep your original Medicare card. Any doctor who accepts Medicare accepts your Medigap plan. No networks, no referrals, no surprise bills from out-of-state providers while you travel.
Cost Comparison: What You Actually Pay
Medicare Advantage appears cheaper because many plans charge $0 per month. But your total annual cost depends on how much healthcare you actually use. A healthy year can favor Advantage. A high-use year — a surgery, a hospital stay, a new diagnosis — can quickly change that math.
If you are healthy and rarely use coverage, Medicare Advantage often costs less because the premiums are low. But once you start using more care, the copays accumulate quickly. With Plan G, once you have paid the $283 deductible, Medicare and your Medigap policy cover the rest at 100%.
The $9,350 exposure on Advantage plans is real.A difficult health year — surgery, extended hospitalization, a serious new diagnosis — could push you close to your plan's annual out-of-pocket maximum. That financial risk is the direct tradeoff for lower monthly premiums.
How the two plans actually compare
Here is how Medicare Advantage stacks up against a Medicare Supplement Plan G on the things our clients ask about most.
| Medicare Advantage | Medigap Plan G | |
|---|---|---|
| Doctor networks | Restricted to plan's HMO or PPO network | Any provider who accepts Medicare |
| Referrals | Often required on HMO plans | Not required |
| Monthly premium | $0 to about $50 on most plans | $130–$200 per month for Plan G |
| Annual out-of-pocket exposure | Up to $9,350 per year | Generally just the $283 Part B deductible |
| Predictability of costs | Varies with how much care you use | Very predictable year to year |
| Prior authorization | Common for procedures and imaging | Rarely required |
| Dental, vision, hearing | Often bundled in | Not included (sold separately) |
| Prescription drug coverage | Usually built into the plan | Requires a separate Part D plan |
| Travel outside your service area | Emergency care only | Works nationwide with any Medicare provider |
| Year-to-year stability | Benefits and networks can change annually | Federally standardized benefits |
Bolded cells show which plan typically has the edge on that point. Neither plan is "better" across the board — the right one depends on your health, your doctors, and your budget.
Who Should Choose Which Plan?
There is no universal right answer. The best plan depends on your health, your doctors, how often you use care, and what matters most to you.
- Are generally healthy with infrequent medical needs
- Want to keep monthly costs as low as possible
- Want dental, vision, and hearing in one plan
- Have local doctors you trust who are in-network
- Live in one area year-round
- Are comfortable managing copays as you go
- Have a chronic condition or see multiple specialists
- Want predictable costs with no surprise bills
- Travel frequently or split time between states
- Want freedom to see any doctor who accepts Medicare
- Anticipate significant medical care ahead
- Dislike networks, referrals, and prior authorizations
The switching warning most people never hear.If you enroll in Medicare Advantage first and later want to move to a Medigap plan, you may need to pass medical underwriting in most states. A pre-existing condition could result in a denial or a much higher premium. Your Medigap Open Enrollment Period is the 6 months starting the month your Part B becomes effective at age 65 or older. Miss that window and your options narrow significantly.
Plan G vs. Plan N: The Two Medigap Plans Worth Comparing
If you decide a Medicare Supplement is the right path, the next decision is which plan letter to choose. For most people in 2026, it comes down to Plan G or Plan N. Both work the same way alongside Original Medicare. The difference is how the costs are split.
- You pay the $283 Part B deductible. After that, covered care is paid at 100%.
- No copays at the doctor, no copays at the ER, no surprise bills for covered services.
- Best fit if you want the most predictable Medicare experience available.
- Lower monthly premium than Plan G in exchange for small copays at the point of care.
- Up to $20 per office visit and up to $50 for an ER visit that does not turn into a hospital admission.
- Best fit for healthier members who want strong protection without the higher Plan G premium.
There is also a third option worth knowing about: High Deductible Plan G (HDG). It carries a much lower monthly premium and a single calendar-year deductible. Once you meet it, the plan behaves exactly like standard Plan G. It is the lowest-premium Medigap option in Alabama and pairs well with a separate hospital indemnity plan for people who want the network freedom of Medigap without the full Plan G premium.
Enrollment Timing: The Window That Decides Your Options
The single most important enrollment rule in Medicare is one most people never hear about until it is too late. The plan you start with is often the plan you can keep. Switching later is not always allowed without health questions.
Your Medigap Open Enrollment Period is the 6 months starting the month your Part B becomes effective at age 65 or older. During this window, every insurer must offer you any Medigap plan at the best available rate, regardless of your health history. You cannot be denied and you cannot be charged more for pre-existing conditions. This window does not repeat.
AEP is when you can join, drop, or switch a Medicare Advantage plan or a Part D prescription plan. It is not a guaranteed window for adding a Medigap policy. Coverage changes made during AEP take effect January 1.
If you are already enrolled in a Medicare Advantage plan, this window lets you switch to a different Advantage plan or return to Original Medicare. Moving back to Original Medicare allows you to apply for a Medigap plan, but most states still require medical underwriting outside your original six-month window.
Why the order matters.Starting on Medicare Advantage and trying to move to Medigap later is the most common mistake we see. If your health has changed at all in those years, an insurer can decline you, exclude conditions, or charge a substantially higher premium. Choosing Medigap during your initial Open Enrollment locks in your guaranteed acceptance for life.
Frequently Asked Questions
Not Sure Which Plan Fits Your Situation?
Every Medicare decision is personal. As a PharmD and licensed Medicare broker, I review your medications, your doctors, and your health history to find the plan that actually works for your life — at no cost to you.
Tyler is a Doctor of Pharmacy and licensed Medicare broker helping families across Alabama and the Southeast choose the right Medicare plan. Backed by lifetime claims and billing support — at no cost to you.