Every fall, millions of Americans age 65 and older make a choice that can swing their annual health costs by thousands of dollars — and most of them don't realize it until the bills arrive.
The decision comes down to Medicare Advantage versus Medigap, also called a Medicare supplement.
Medicare Advantage, offered by private insurers, bundles hospital, medical, and usually drug coverage into one plan.
Premiums can run as low as $0 beyond the standard Part B charge, which is why roughly half of eligible beneficiaries now pick it.
The catch sits in the fine print: deductibles, copays, and annual out-of-pocket maximums that climbed to $9,350 for in-network care in 2025.
You keep Original Medicare and buy a private supplemental policy that covers most of what Medicare doesn't — deductibles, coinsurance, and in many cases nearly all of it.
Premiums run higher, often $100 to $250 a month depending on your state and plan letter.
In exchange, your financial exposure shrinks dramatically.
The trade-off is predictable costs versus lower upfront ones.
Medicare Advantage plans also come with networks.
See an out-of-network specialist and you may pay the full bill.
Medigap, by contrast, lets you use any provider in the country who accepts Medicare — a real advantage for snowbirds and anyone who travels for care.
You get a one-time, six-month Medigap open enrollment window that starts the month you're 65 and enrolled in Part B.
Miss it, and insurers in most states can charge you more or reject you outright based on health history.
Only a handful of states, including New York and Connecticut, offer year-round guaranteed acceptance.
That asymmetry is why many financial planners describe the Medigap decision as a now-or-never moment.
Choosing Medicare Advantage first and switching later can mean passing medical underwriting — and paying a permanently higher premium if you have a chronic condition.
Medicare Advantage plans typically include Part D.
Standalone Medigap policies do not, so you'd buy a separate drug plan, which brings its own premium and formulary.
The Centers for Medicare & Medicaid Services projects average Medicare Advantage premiums will dip slightly for 2025, while standalone Part D premiums are set to fall after the $2,000 annual cap on out-of-pocket drug costs took effect.
Those headline numbers are real, but they don't capture the specialist visits, imaging, and hospital stays where Advantage cost-sharing adds up.
Extra benefits muddy the comparison further.
Many Advantage plans throw in dental, vision, hearing aids, gym memberships, and grocery allowances.
Those perks are genuine — and they're also a marketing engine.
The practical test isn't which plan looks cheaper in January.
A cancer diagnosis, a hip replacement, or a stint in a skilled nursing facility can turn a low-premium Advantage plan into a five-figure bill.
A Medigap policy turns that same year into a manageable, predictable number.
Review your current plan's "Evidence of Coverage" document, not the brochure.
Check the out-of-pocket maximum, the specialist copay, and whether your doctors are still in network.
If you're healthy, mobile, and cost-conscious, Advantage can work well.
If you want budget certainty and nationwide access, Medigap usually wins.
The honest takeaway: this is one of the few financial decisions where the cheaper option often carries the bigger long-term price tag.
Final Thoughts
Run your own numbers against your own health history — and if you're still working past 65 or planning to move, factor that in before the enrollment window closes.