Every fall, millions of Americans on Medicare face the same fork in the road, and the wrong turn can cost thousands.
The choice comes down to two very different products: Medicare Advantage (Part C) and Medicare Supplement plans, often called Medigap.
They behave nothing alike when the bills arrive.
Medicare Advantage is the all-in-one route.
Private insurers bundle your Part A and Part B coverage, usually add drug coverage and extras like dental or vision, and often charge a $0 premium beyond the standard Part B amount.
You generally stay inside the plan's network, referrals are common, and out-of-pocket costs are capped but the cap can run past $8,000 a year for in-network care.
You keep original Medicare, see any provider nationwide who accepts it, and skip referrals entirely.
A supplement plan then picks up most of what Medicare leaves behind, from copays to coinsurance.
The catch is the price: premiums commonly run $100 to $250 a month depending on your state, age, and plan letter, and that's on top of Part B.
Someone who sees a handful of doctors and takes a few generics might come out ahead with Advantage, especially with the extra perks.
Someone managing a chronic condition, seeing specialists, or traveling often may find Medigap's predictable costs worth every dollar.
There's a deadline that changes everything.
When you first enroll in Medicare at 65, you get a six-month window where insurers must sell you any Medigap policy at standard rates, regardless of your health history.
Miss it, and in most states you can be rejected or charged more because of pre-existing conditions.
A few states, including New York and Connecticut, offer year-round protections, but most don't.
That single rule is why advisors tell healthy 65-year-olds to at least look hard at Medigap now.
Switching later isn't just a paperwork exercise.
It can be medically underwritten, meaning the door may simply close.
Meanwhile, Medicare Advantage lets you change plans every year during open enrollment, which is flexible but also means your network and copays can shift under you.
Prescription drugs complicate the picture further.
Advantage plans usually include Part D, while Medigap enrollees buy a separate drug plan.
Formularies change annually, and a medication that costs $20 this year can jump tiers next year.
Checking your specific drug list against each plan before enrolling is not optional.
It's the difference between a manageable bill and a nasty surprise in January.
Advantage ads flood the airwaves with gym memberships and grocery allowances, and those extras are real.
But so are prior authorizations, which can delay or deny care.
Medigap has no network and no prior authorization for covered services, which is exactly what you're paying for.
My take: run your own numbers with your own doctors and prescriptions before you decide.
If you can afford Medigap at 65, locking in that flexibility early is hard to undo later.
Final Thoughts
If premiums stretch your budget, Advantage can work, but read the out-of-pocket cap and network rules carefully.