Medicare Advantage vs. Medigap: The Real Difference

Sooner or later, almost everyone new to Medicare hits the same fork in the road: Medicare Advantage, or a Medigap supplement? Both are legitimate and both are popular, so the right pick is genuinely personal. The trouble is that most people decide on the factor that matters least — the monthly premium. Here's what should actually drive the choice.

The quick answer

Medicare Advantage and a Medigap supplement are two different ways to cover the gaps Original Medicare leaves behind — you choose one, not both. As a rule of thumb, Advantage usually costs less while you're healthy, and Medigap usually costs less when you're sick. The most important catch: switching from Advantage to Medigap later can require passing medical underwriting, so the first choice matters more than it looks.

First, what they're both trying to fix

Original Medicare (Part A and Part B) is good coverage, but it has gaps. After your deductibles, Part B generally pays about 80% and you pay the other 20% — with no cap on what that 20% can add up to in a bad year. In 2026 the Part B deductible is $283, and the inpatient hospital deductible is $1,736 per benefit period.

There are two different ways to deal with those gaps. You pick one:

• Medicare Advantage (Part C) — a private plan that replaces how you get your Medicare, usually bundling in drug coverage and extras.
• A Medigap supplement — a private policy that works alongside Original Medicare and pays the gaps it leaves behind (you add a separate Part D drug plan).

The side-by-side

	Medicare Advantage	Medigap (Supplement)
Monthly premium	Often low or $0 (you still pay your Part B premium)	Higher — a set monthly premium
Doctors	Network-based (HMO/PPO); referrals & prior approval common	Any doctor or hospital in the U.S. that takes Medicare
Costs when you get care	Copays & coinsurance as you go, up to a yearly out-of-pocket max	Little to nothing at the point of care (depends on plan)
Drug coverage	Usually built in	Separate Part D plan needed
Extras (dental, vision, etc.)	Often included	Not included
Best for	Lower upfront cost, OK with a network	Predictability & freedom to go anywhere

 

The trade-off in one sentence

Medicare Advantage usually costs less when you're healthy; Medigap usually costs less when you're sick. Advantage keeps your monthly bill low, but you pay as you use care, within a network and sometimes after prior authorization. Medigap costs more every month but smooths everything out — you can see almost any doctor, and your bills are predictable even in a rough year.

For most people, the network question comes down to one thing: are the doctors and hospitals you rely on in the plan's network? With a Medigap supplement that question disappears, because Original Medicare has no network — any provider who accepts Medicare works. With Advantage, it's worth confirming your specific doctors and hospital before you enroll.

Good news on drug costs either way.

Medicare now puts a hard cap on what you pay out of pocket for covered prescription drugs each year. In 2026 that cap is $2,100. It applies whether your Part D is built into an Advantage plan or it's a standalone plan paired with Medigap.

The part most people miss: medical underwriting

Here's the catch that makes this decision bigger than it looks. When you first turn 65 and enroll in Part B, you get a 6-month Medigap Open Enrollment Period. During that window, a supplement company must sell you a policy — they can't turn you down or charge you more for your health history.

After that window closes, in most states, buying or switching a Medigap policy can require medical underwriting. That means the insurer can review your health and deny you or charge more. (A handful of states have their own rules that limit or remove underwriting — for example, New York and Massachusetts guarantee Medigap year-round, and several others offer annual windows — so it's worth knowing the rules where you live.)

Why does that matter for this choice? Because if you start on Medicare Advantage and later decide you want the freedom of Medigap, you may have to pass underwriting to get it — and if your health has changed, that door can be hard to open. It's not impossible, and there are special situations that protect you, but it's the single most important thing to understand before you choose.

Bottom line:

Don't pick on premium alone. Think about the doctors you want to keep, how predictable you need your costs to be, and the underwriting rules down the road. That's a 15-minute conversation — and it's worth getting right the first time.

Quick recap

• Original Medicare leaves gaps with no cap on your share — you fill them with either Medicare Advantage or a Medigap supplement.
• Advantage usually costs less monthly but uses networks and prior authorization.
• Medigap costs more monthly but lets you see almost any doctor, with predictable costs.
• A separate Part D drug plan pairs with Medigap; Advantage usually builds drug coverage in.
• Switching from Advantage to Medigap later can require medical underwriting in most states — so choose carefully up front.

Common questions

Are Medicare Advantage and Medigap the same thing?

No. They're two different ways to cover the gaps in Original Medicare, and you pick one, not both. Medicare Advantage replaces how you get your Medicare through a private plan; a Medigap supplement works alongside Original Medicare and pays the gaps it leaves behind.

Which one lets me keep my own doctors?

A Medigap supplement lets you see any doctor or hospital in the country that accepts Medicare, with no network. Medicare Advantage plans use networks (HMO or PPO), so you'll want to confirm your doctors and hospital are in-network before enrolling.

Which is cheaper?

Advantage usually has the lower monthly premium (often $0, though you still pay your Part B premium), but you pay copays and coinsurance as you use care. Medigap has a higher monthly premium but little to nothing at the point of care. In short: Advantage tends to cost less when you're healthy, Medigap when you're sick.

How do I get prescription drug coverage with each?

Most Medicare Advantage plans build drug coverage in. With a Medigap supplement, you add a separate standalone Part D plan. Either way, in 2026 your out-of-pocket cost for covered drugs is capped at $2,100 for the year.

Can I switch from Advantage to Medigap later?

Sometimes, but not always easily. After your one-time 6-month Medigap Open Enrollment Period, most states allow insurers to use medical underwriting, meaning they can charge you more or decline you based on your health. That's why it's important to understand the trade-off before you choose, not after.

Still torn between Advantage and Medigap?

Our licensed agents will compare both against your own doctors, hospitals, and prescriptions — at no cost and with no pressure — so you can choose with confidence.