Turning 65 comes with a decision that quietly shapes your finances for the rest of your life, and most people make it without fully understanding the trade-offs.
Medicare Advantage and Medicare Supplement plans sound similar, but they work in opposite ways.
Pick wrong and you could be staring down bills you never saw coming.
Medicare Advantage, often called Part C, is the all-in-one route.
Private insurers bundle your hospital, doctor, and drug coverage, and many plans advertise $0 monthly premiums.
The catch shows up later in copays, coinsurance, and a yearly out-of-pocket maximum that can stretch past $8,000 for in-network care.
Medicare Supplement plans, also known as Medigap, take the opposite approach.
You pay a predictable monthly premium, often $100 to $250 depending on your state and plan letter, and the policy covers most of what original Medicare leaves behind.
A healthy 65-year-old on a $0 premium Advantage plan might pay a few hundred dollars a year in copays, making it the cheaper short-term play.
But add a hospital stay, a specialist, or a new diagnosis, and those costs can climb fast.
Medigap's higher premium buys something Advantage can't: predictability when your health turns.
With Medicare Advantage, your doctors and hospitals must be in network, and networks change every year.
You can check whether your providers are covered through Medicare's Plan Finder.
If your specialist drops the plan, you're stuck switching or paying out of pocket.
Medigap lets you keep any provider who accepts Medicare nationwide.
Advantage plans usually include Part D, but formularies and tiers shift annually.
Medigap alone doesn't cover prescriptions, so you'd pair it with a standalone Part D plan.
Compare total drug costs, not just premiums, using Medicare's official plan comparison tool before deciding.
Timing matters more than most people realize.
When you first enroll in Medicare, you get a one-time Medigap open enrollment window that lasts six months.
During that window, insurers can't charge you more or deny coverage because of your health history.
Miss it, and you may face medical underwriting, higher premiums, or outright rejection in most states.
That window is the single most important deadline in this entire decision, and it's why financial advisors often tell clients to seriously weigh Medigap early.
Switching from Advantage to Medigap later isn't guaranteed.
A few states, including New York and Connecticut, offer more flexible rules, but most don't.
It depends on your budget, your health, and your tolerance for uncertainty.
If you can afford higher premiums and want fewer surprises, Medigap tends to age better.
If cash flow is tight and you're comfortable with networks and copays, Advantage can work, as long as you read the fine print and revisit your choice every fall during open enrollment.
Our take: treat this like any other major financial commitment, not a one-time checkbox.
Run your actual prescriptions and doctors through Medicare's tools, factor in a bad-health year, and don't let a $0 premium lure you past the math.
Final Thoughts
The cheapest plan today is rarely the cheapest plan over a decade.