If you're turning 65 this year, you're about to face a decision that will follow you for the rest of your life — and the wrong pick can quietly drain your savings.
The two main paths are Medicare Advantage (Part C) and Medicare Supplement plans, also called Medigap.
Medicare Advantage is run by private insurers who contract with the government.
You often get extra perks like dental, vision, and gym memberships, and many plans charge a $0 premium on top of your Part B payment.
That low upfront number is why roughly half of eligible Americans now choose Advantage.
You pay a private insurer a monthly premium — often $100 to $200 or more depending on your state and age — and in exchange, the plan covers most or all of the gaps left by original Medicare.
You see any doctor in the country who accepts Medicare.
The catch with Advantage is the fine print.
These plans use networks, prior authorizations, and copays that can add up fast if you get seriously ill.
A 2023 KFF analysis found that a small share of Advantage prior-authorization denials were later overturned on appeal — meaning some patients were initially told no for care they were entitled to.
You pay more every month, whether you use it or not.
But when something big happens — a cancer diagnosis, a hip replacement, a week in the hospital — the bill is largely someone else's problem.
When you first enroll in Medicare Part B, you get a six-month Medigap open enrollment window.
During that window, insurers in most states must sell you a policy regardless of your health history.
Miss it, and you can be denied or charged more for pre-existing conditions.
That single deadline is why financial planners often tell healthy 65-year-olds to at least consider Medigap first.
You can always switch to Advantage later in most states.
Going the other direction is where people get stuck.
Formularies shift, networks shrink, and premiums move.
A plan that fits your doctors today may not fit them in 2027.
The honest answer is that neither option wins for everyone.
If you travel a lot, have chronic conditions, or see specialists at a major hospital, Medigap's predictability is often worth the premium.
If you're healthy, cost-conscious, and comfortable staying in-network, Advantage can work well for years.
What you shouldn't do is pick based on the TV ad with the smiling couple.
Compare the actual drug costs, the actual doctors, and the actual out-of-pocket maximum — not the headline premium.
Opinion: This isn't a political fight, it's a math problem with your name on it.
Spend two hours with a licensed counselor before you check a box you can't easily uncheck.
Final Thoughts
The plan that saves you $80 a month today can cost you $8,000 in a bad year.