Every fall, roughly 60 million Americans on Medicare get buried in glossy mailers promising dental, vision, and "$0 premiums." The pitch sounds like a steal.
But the people selling those plans aren't doing it out of charity, and the difference between Medicare Advantage and a Medigap supplement is the single most expensive decision most retirees will ever make without reading the fine print.
Original Medicare (Parts A and B) covers hospital and doctor visits but leaves you on the hook for 20 percent of most outpatient costs, with no annual cap.
A Medicare Supplement plan, often called Medigap, picks up most of that gap.
You pay a monthly premium, and in exchange, your out-of-pocket exposure shrinks to nearly nothing.
Medicare Advantage is a different animal entirely.
It's a private insurance plan that replaces Original Medicare, usually with a low or zero premium and extras like gym memberships and hearing aids.
The trade-off: you're locked into the plan's network, you often need referrals, and care can require prior authorization.
Where it gets ugly is when people get sick.
Advantage plans can deny or delay care through prior authorization, a process that a 2023 federal watchdog report found frequently resulted in denials that were later overturned on appeal.
If you're healthy, that may never matter.
If you're diagnosed with cancer or need a specialist, it can matter a lot.
Switching back to a supplement later is possible, but in most states insurers can medically underwrite you, meaning they can charge more or reject you outright.
Medigap premiums run roughly $100 to $200 or more per month depending on your age, state, and plan letter.
Advantage plans keep premiums near zero but shift costs into copays, coinsurance, and annual maximums that can climb into the thousands if you use a lot of care.
The broker pitching Advantage usually earns a commission either way, so "free" advice is rarely free.
Advantage plans change their networks, drug formularies, and copays every single year.
A plan that covered your prescriptions in January might drop them by the next plan year, and you may not find out until you're at the pharmacy counter.
Supplements, by contrast, tend to be far more stable once you're enrolled.
If you're relatively healthy, take few medications, and want to keep monthly costs low, Advantage can pencil out.
If you have chronic conditions, travel, or want the freedom to see any specialist without a fight, a supplement plus a standalone drug plan is often the safer bet, even at a higher monthly cost.
The catch is that the decision is easiest to make when you're first eligible.
Wait, and your options narrow. **The takeaway:** Nobody is handing you free healthcare.
Advantage plans are cheaper up front because they take on more control over your care, and supplements cost more monthly because they take on more of your risk.
Final Thoughts
Read the summary of benefits, check whether your doctors and drugs are actually covered, and ask the person selling you a plan exactly how they get paid.