Every fall, millions of Americans on Medicare face the same confusing fork in the road: stick with Original Medicare plus a supplement plan, or switch to a Medicare Advantage plan with a tempting $0 monthly premium.
The difference between these two paths can add up to thousands of dollars a year, and picking wrong is one of the most expensive mistakes retirees make.
Original Medicare covers hospital and doctor visits but leaves you on the hook for 20% of most outpatient costs with no annual cap.
A Medigap supplement picks up most of that leftover tab, but you pay a monthly premium for the privilege.
Medicare Advantage, by contrast, bundles everything into one plan, often throws in dental, vision, and gym memberships, and advertises that $0 premium loud and clear.
Advantage plans come with copays, coinsurance, and an out-of-pocket maximum that can run past $8,000 a year for in-network care.
Medigap plans have higher monthly premiums but far more predictable costs, and many cover nearly everything Medicare doesn't.
Medicare Advantage plans typically use HMOs or PPOs, meaning you may need referrals, stay in-network, and get prior authorization for certain procedures.
Original Medicare with a supplement lets you see almost any doctor in the country who accepts Medicare.
If you travel or split time between states, that flexibility matters.
There's also a deadline most people don't know about.
When you first enroll in Medicare Part B, you get a six-month Medigap open enrollment window where insurers must sell you a policy regardless of your health history.
Miss it, and you could be denied coverage or charged more later because of preexisting conditions.
Advantage plans don't have that problem, but they can change their provider networks and drug formularies every single year.
Standalone Part D plans pair with Original Medicare and Medigap, while most Advantage plans include prescriptions.
The trade-off is that Advantage drug lists can shift annually, so a medication that's cheap this year might jump in price next year.
It depends on your health, your budget, and how much uncertainty you can stomach.
If you're relatively healthy and want low upfront costs, Advantage can work well.
If you have ongoing medical needs or want to avoid surprise bills, a supplement often pays off despite the higher premium.
Either way, check whether your doctors are in-network, add up realistic annual costs, and review your plan every open enrollment period.
The bottom line: the cheapest-looking plan isn't always the cheapest plan.
Final Thoughts
Run the numbers for your own situation before you commit, because switching later isn't always easy or allowed.