Picking between Medicare Advantage and a Medigap supplement is one of the few retirement decisions you can't easily undo, and the wrong pick can follow your wallet for years.
Both replace the gaps in original Medicare, but they work in completely opposite ways.
One hands you a low premium and a network.
The other hands you a higher premium and near-total freedom.
Medicare Advantage, known as Part C, is run by private insurers.
You often pay $0 or a small monthly premium on top of your Part B fee, and many plans throw in dental, vision, hearing, and drug coverage.
That low upfront number is why roughly half of eligible Americans now choose it.
The catch hides in the fine print: deductibles, copays, and a yearly out-of-pocket maximum that can climb past $8,000 for in-network care.
A Medigap supplement works nothing like that.
You buy it alongside original Medicare, and it picks up most of what Medicare leaves behind — coinsurance, copays, deductibles.
There are no networks, so any doctor or hospital in the country that takes Medicare takes you.
A Plan G supplement can run $120 to $200 a month depending on your age and state, and that's before your Part B premium.
Here's where the math gets uncomfortable.
Advantage looks cheap until you actually get sick.
A few hospital stays or a course of cancer treatment can trigger thousands in copays that a supplement would have absorbed.
One study found Advantage enrollees with serious illness faced meaningfully higher costs than those with traditional Medicare plus a supplement, even after the low premiums were factored in.
The rules also differ in ways people don't discover until it's too late.
You can join, switch, or drop an Advantage plan during open enrollment each fall.
In most states, you get a one-time window to buy a supplement without health questions, and after that insurers can reject you or charge more because of your medical history.
Switch to Advantage for a few years, develop a condition, and you may not be able to buy your way back.
Advantage plans are easy to enter and easy to leave — until your health changes.
Medigap is harder to enter and easier to keep.
If you can afford the premium and want predictable bills, a supplement often wins over the long haul.
If the monthly cost is genuinely out of reach, Advantage can still be a reasonable safety net.
Advantage plans can deny care that isn't medically necessary in their view, and prior authorization remains a frequent complaint.
Supplements don't cover drugs, so you'd still buy a Part D plan, and they won't pay for dental or vision.
Run your own prescriptions and doctors through each plan's formulary and network before you decide.
Our take: treat this as a bet on your future health, not your current bank balance.
If you have savings and any chronic condition, the supplement's higher premium buys something real — freedom to see any doctor and bills that don't spike when you get sick.
Final Thoughts
If cash is tight, an Advantage plan can work, but go in knowing the out-of-pocket cap is your true worst-case number.