If you are turning 65 this year, you have roughly seven months to make one of the most expensive decisions of your retirement.
The TV ads promise dental, vision, and a $0 premium.
What they rarely mention is the trade-off buried in the fine print.
The two main paths are Medicare Advantage (Part C) and Original Medicare paired with a Medigap supplement.
They behave nothing alike when you actually get sick.
Medicare Advantage works like an HMO or PPO through a private insurer.
You generally stay in a network, need referrals for specialists, and face copays for each service.
Premiums can be low, sometimes zero beyond your Part B payment, but the costs show up later.
There is no annual out-of-pocket limit on Original Medicare, but Advantage plans do cap spending, typically between $3,000 and $8,000 in-network before the plan covers everything.
You pay a monthly premium, often $100 to $200 depending on your state and age, plus a separate Part D drug plan.
In exchange, Medigap picks up most of what Medicare does not.
Any doctor in the country who accepts Medicare takes you.
You get a one-time Medigap open enrollment window that starts the month you turn 65 and enroll in Part B.
During that window, insurers cannot reject you or charge more because of your health history.
Miss it, and a single diagnosis can lock you out of the cheapest plans permanently.
That detail is why financial planners keep repeating the same advice: if you can afford the premium, buy the supplement first.
You can always drop it later for Advantage.
Going the other direction is where people get trapped.
Advantage plans have quietly become the default.
More than half of eligible Americans are now enrolled, drawn by the zero-premium pitch and extra perks.
Insurers also get paid more when they code your conditions aggressively, which is why the ads never stop.
A healthy 67-year-old on an Advantage plan may pay almost nothing for years and feel like a genius.
Suddenly there are prior authorizations, network specialists, and a stack of denials to appeal while you are exhausted and scared.
A supplement holder in the same situation mostly just shows their card.
If you have limited savings, take expensive brand-name drugs, or live in an area with a strong local network, the low premium can be the only realistic option.
The mistake is choosing based on the monthly number alone instead of the worst-case year.
Add up the maximum out-of-pocket limit plus premiums for each option over a full year.
Ask your doctors directly which plans they accept and whether they require referrals.
And check your state's rules, because a handful of states let you switch from Advantage to a supplement later without health screening, and most do not.
Open enrollment for Advantage and Part D runs October 15 through December 7.
Medigap has no annual window, but that health-based underwriting clock never restarts.
The honest take: this is not really a comparison between two products.
It is a bet on your own future health and your ability to absorb a bad year.
If you have the savings, paying more each month for fewer surprises is usually the safer trade.
Final Thoughts
If you do not, go in with your eyes open and read the out-of-pocket cap, not the premium.