Medicare's annual open enrollment runs through December 7, and for the roughly 68 million Americans on the program, the choice between Medicare Advantage and Medigap has never carried a bigger price tag.
The two paths look similar on a brochure.
They behave nothing alike once the bills arrive.
Medicare Advantage, often called Part C, is the all-in-one route.
Private insurers like UnitedHealthcare, Humana, and CVS's Aetna administer your benefits, frequently bundling dental, vision, and hearing coverage with a $0 or low monthly premium.
The trade-off hides in the fine print: copays, coinsurance, prior authorizations, and provider networks that can shift every January.
Medigap, or Medicare Supplement, works differently.
You keep original Medicare and buy a private policy that covers most of what Medicare doesn't.
Premiums run higher—often $100 to $250 a month depending on your state and plan letter—but the coverage is standardized.
A Plan G in Ohio covers the same things as a Plan G in Oregon.
The real gap shows up when care gets expensive.
A Medigap Plan G holder typically pays one deductible (about $283 in 2025) and then almost nothing for covered care.
An Advantage enrollee can face a hospital stay copay of $300 or more per day, plus 20% coinsurance on many services—capped only by an out-of-pocket maximum that can reach $9,350 in-network.
That ceiling sounds reassuring until you learn Advantage plans also control the care itself.
Insurers can require prior authorization for procedures, skilled nursing, and even some imaging.
A 2023 federal report found that some Medicare Advantage denials were later overturned on appeal, but most patients never appeal.
Medigap buyers face a different catch: underwriting.
Outside a limited window when you first turn 65, most states let insurers charge more or deny you outright based on health history.
Switch back from Advantage after a few years and you may not qualify for the supplement you want.
Medigap doesn't, so you'll need a standalone Part D policy—cheap on paper, but premiums are rising and formularies keep tightening.
Consumer advocates say the deciding factor is usually health and finances, not marketing. "If you can afford the premium and have ongoing conditions, Medigap gives you predictability," said one benefits counselor. "If you're healthy and want the lowest monthly cost, Advantage can work—until it doesn't." There's also a quiet enrollment trap.
Miss the window and you're locked in for another year.
Medigap shoppers, by contrast, can generally switch plans anytime, though the new insurer may still screen them.
Free counseling is available through your State Health Insurance Assistance Program, or SHIP, and through Medicare.gov's plan finder.
The numbers change by ZIP code, so a plan that's cheap in Tampa can be pricey in Tucson.
The deadline is December 7 for coverage starting January 1.
After that, most people wait until next fall.
Our take: treat this like a car purchase, not a coupon clipping.
The lowest premium is rarely the lowest total cost once you actually need care.
Final Thoughts
Run your own prescriptions and doctors through Medicare.gov before you decide—twenty minutes now can save you thousands later.