If you're turning 65 this year, you're about to get buried in mail about Medicare plans.
And the biggest decision you'll face isn't which insurance company to pick.
It's whether to go with Medicare Advantage or a Medicare Supplement plan.
Get it wrong, and the difference could cost you thousands of dollars a year.
Original Medicare (Part A and B) covers hospital stays and doctor visits, but it leaves gaps.
You still pay deductibles, coinsurance, and there's no cap on what you could owe in a bad year.
Both Medicare Advantage and Supplement plans exist to fill those gaps.
They just do it in completely different ways.
Medicare Advantage, also called Part C, is run by private insurers.
You often get extra perks like dental, vision, hearing, and gym memberships.
Many plans advertise $0 monthly premiums, which sounds great.
The catch is what happens when you actually need care.
You're locked into the plan's network, you may need referrals to see specialists, and every service comes with copays.
There's an annual out-of-pocket maximum, but in 2025 it can run as high as $9,350 for in-network care.
Medicare Supplement plans, often called Medigap, work differently.
You keep Original Medicare and add a policy that picks up most of what Medicare doesn't pay.
Premiums are higher, usually $100 to $250 a month depending on your state and plan letter.
You can see any doctor in the country who accepts Medicare.
And once you pay your Part B deductible, many plans cover nearly everything else.
That network difference matters more than people realize.
If you travel, snowbird, or want to see a specialist at a top hospital, Medigap gives you freedom that most Advantage plans don't.
Advantage plans are built around local networks, so a doctor you love now might be out of network next year.
The other big difference is how you can switch.
When you first enroll in Medicare, you get a one-time Medigap open enrollment window.
During those six months, insurers can't turn you down or charge you more because of health problems.
Miss that window, and you may need to pass medical underwriting to buy a supplement later.
Advantage plans, by contrast, let you switch every year during open enrollment, but you can't easily move back to Medigap if your health has changed.
If you're healthy and rarely see a doctor, a low-premium Advantage plan can save real money.
If you have chronic conditions, see multiple specialists, or just want predictable bills, Medigap often wins, even with the higher monthly payment.
Run the math on your actual prescriptions too.
Advantage plans often use their own drug coverage, while Medigap pairs with a separate Part D plan.
One more thing: check whether your doctors and hospital are in an Advantage plan's network before you sign up.
A plan that looks cheap on paper is worthless if it doesn't cover the doctors you trust.
The honest take: there's no universal winner here, and anyone who tells you otherwise is selling something.
But if you can afford the premiums and want fewer surprises, Medigap is usually the safer long-term bet.
Final Thoughts
Read the fine print, compare total yearly costs, not just the monthly number, and decide based on your health and how you actually live.