Medicare's annual open enrollment window closes December 7, and for the roughly 68 million Americans on the program, the choice between Medicare Advantage and a Medicare Supplement plan is the single most expensive decision most people will make this year.
The two paths look similar on a brochure.
Medicare Advantage, known as Part C, is the all-in-one option.
Private insurers administer your benefits, often bundling dental, vision, hearing and prescription drug coverage into one plan, frequently with a $0 monthly premium.
The trade-off is networks: you generally must use in-network doctors and hospitals, and you may need referrals for specialists.
Insurers can also change coverage, provider lists and prior-authorization rules every year.
Medicare Supplement plans, also called Medigap, work differently.
You keep original Medicare and buy a private policy that covers most of what Medicare doesn't — deductibles, copays and coinsurance.
There are no networks, so any provider who accepts Medicare takes your plan.
But you pay a monthly premium that varies by state, age and insurer, often running $100 to $200 or more per month.
A healthy 65-year-old who rarely sees a doctor might pay almost nothing in premiums with Advantage and come out ahead.
A person managing diabetes, heart disease or cancer can blow past that savings fast through copays, out-of-network bills and prior-authorization fights.
There's a deadline trap most people miss.
You can only buy a Medigap policy with guaranteed acceptance during your six-month Medigap Open Enrollment Period, which starts the month you're 65 and enrolled in Part B.
After that window, insurers in most states can reject you or charge more based on your health history.
Switching from Advantage back to a Supplement later can mean answering medical questions — and getting denied.
One more catch: if you enroll in Medicare Advantage first and want out, you get a trial right during your first year.
After that, you're generally locked into underwriting in most states, with a handful of exceptions like New York and Connecticut that offer more flexibility year-round.
Advantage plans have grown fast — now covering more than half of all Medicare beneficiaries — partly because of those $0 premiums and extra perks like gym memberships and over-the-counter allowances.
Regulators have pushed back on marketing tactics, and a recent government review found some plans overbilled for diagnoses, which can affect future costs.
Before December 7, check whether your doctors are in a plan's network, add up your realistic drug costs using Medicare's Plan Finder, and compare total annual spending — not just the monthly premium.
The cheapest sticker price is rarely the cheapest year. **Our take:** The premium you see advertised is only half the story.
If you have ongoing health issues or want to keep any doctor you choose, a Supplement's higher monthly cost often buys real peace of mind.
Final Thoughts
If you're healthy and cost-focused, Advantage can work — just read the fine print before the deadline passes.