If you're turning 65 or reviewing your Medicare coverage this fall, you're staring down one of the most expensive decisions in retirement.
The split between Medicare Advantage and Medicare Supplement plans isn't just a paperwork difference — it can swing your yearly out-of-pocket costs by thousands of dollars.
Medicare Advantage (Part C) works like an HMO or PPO.
Private insurers bundle your hospital and doctor coverage, often toss in dental, vision, and hearing, and frequently charge a $0 monthly premium.
That low upfront price is why nearly half of eligible Americans have switched.
But the trade-off is real: copays, networks, and prior authorizations.
Medicare Supplement plans, also called Medigap, work differently.
You keep original Medicare and buy a private policy that covers most of what Medicare leaves behind — deductibles, coinsurance, and hospital costs.
Premiums run higher, sometimes $150 to $250 a month depending on your state and age.
In exchange, your out-of-pocket exposure drops close to zero.
A typical Advantage plan caps annual out-of-pocket spending around $8,850 in 2025 for in-network care.
A Medigap Plan G holder might pay a $257 deductible plus a $283 annual Part B deductible and little else.
One bad hospital stay can erase years of premium savings on the Advantage side.
There's a catch that trips up late switchers.
In most states, Medigap insurers can reject you or charge more after your initial enrollment window closes.
If you pick Advantage at 65 and develop a health issue, moving to a supplement later can be painfully expensive — or impossible.
A handful of states, including New York and Connecticut, offer year-round guaranteed acceptance, but most don't.
Advantage plans often require in-network doctors and referrals.
If you split time between states or see specialists, that friction adds up.
Medigap lets you see any provider who accepts Medicare nationwide, which snowbirds tend to appreciate.
Both paths usually need a separate Part D plan or a built-in drug benefit.
Advantage plans often include drugs, but formularies shift yearly.
Medigap users buy standalone Part D, which means another premium but more flexibility to switch if your medications change.
It depends on your health, your budget, and your tolerance for surprises.
If you're healthy, cost-conscious, and fine with network rules, Advantage can work well.
If you want predictable bills and nationwide access, Medigap usually costs more monthly but less when things go wrong.
Compare the total picture — premiums plus worst-case out-of-pocket limits — not just the monthly number on the brochure.
The real trap is choosing on premium alone.
A $0 plan feels great until a specialist visit or a hospital stay shows up, and by then your window to switch may have closed.
Final Thoughts
Run the worst-case math for both options before you decide, because the cheapest monthly bill rarely stays the cheapest year.