Every fall, millions of Americans on Medicare face the same decision at the kitchen table: stick with a Medicare Advantage plan or pay up for a Medigap supplement.
The price tags look wildly different, and that gap is exactly where people get tripped up.
Medicare Advantage plans often advertise $0 premiums and extras like dental, vision, and gym memberships.
Traditional Medicare plus a Medigap supplement usually means a monthly premium that can run well over $100 depending on your state and age.
But the headline number hides the fine print.
Advantage plans come with networks, prior authorizations, and annual out-of-pocket maximums that can reach $8,850 for in-network care in 2025.
Hit a rough health year and those copays add up fast.
Once you pay the Part B premium, a supplement picks up most of what original Medicare doesn't, and many plans cap your exposure near zero.
There are no networks, so you can see almost any doctor nationwide who accepts Medicare.
If you sign up for Medigap during your six-month Medigap Open Enrollment Period, starting the month you're 65 and enrolled in Part B, insurers generally can't turn you down or charge more for health problems.
Miss that window, and in most states you can be denied or quoted a higher rate.
That single deadline is why advisors often tell healthy 65-year-olds to grab a supplement first.
You can always switch to Advantage later, but going the other direction is far harder.
In high-cost states like Florida and New York, Medigap premiums can climb past $200 a month.
In lower-cost markets, a Plan G might run $110 to $140 for a 65-year-old.
Others have narrow networks that exclude the specialist you've seen for years, or require referrals that slow down care.
Both paths need separate drug coverage, and a plan that looks cheap can sting if your medications land on a high tier.
Always run your actual drug list through each plan's formulary before deciding.
Another trap: Advantage plans are rebranded every year.
Your doctor might be in-network this year and out next year.
Supplements don't have networks, so that particular headache disappears.
It depends on your health, your budget, and your tolerance for surprises.
If you can afford the premium and want predictable costs, a supplement is often the safer long-term bet.
If money is tight and you're comfortable with managed care, Advantage can work well.
The worst move is picking on premium alone.
A $0 plan that costs you $6,000 in copays during a bad year isn't a bargain.
Talk to a licensed counselor through your State Health Insurance Assistance Program, which offers free, unbiased help.
They're not selling anything, and they can model your actual drugs and doctors. **The bottom line:** Medicare Advantage sells low monthly costs, while Medigap sells predictability.
Final Thoughts
Neither is universally right, but the six-month Medigap window is a genuine one-way door, and treating it casually is how people end up locked out of the option they actually wanted.