If you are turning 65 or reviewing your coverage right now, you have probably stared at two very different pitches.
One promises low or $0 monthly premiums with extras like dental and grocery allowances.
The other costs more every month and, on paper, looks like it does less.
That gap is where a lot of retirees get hurt.
The cheap plan and the expensive plan can lead to wildly different bills after a hospital stay, a cancer diagnosis, or a few days in a skilled nursing facility.
Medicare Advantage, also called Part C, is run by private insurers that contract with the government.
You typically stay in a network, get referrals for specialists, and face copays for each service.
Many plans include drug coverage and perks like vision or fitness memberships.
Original Medicare plus a Medigap supplement works differently.
You keep the federal program as your base, then buy a supplement that picks up most of the remaining 20 percent.
There are no networks with most Medigap plans, and you can see any provider who accepts Medicare.
A supplement can run $100 to $200 or more per month, depending on your state, age, and plan letter.
Advantage premiums are often near zero, but the out-of-pocket maximum can reach the federal limit, which sits above $9,000 for in-network care in 2025.
That difference matters most when you actually get sick.
A Medicare Advantage enrollee with a serious illness may pay thousands in copays before the cap kicks in.
A Medigap Plan G holder typically pays a small deductible and then very little for covered care.
There is another trap that catches people who start with Advantage.
In most states, you can be medically underwritten if you try to switch to a supplement later.
A new diagnosis of diabetes, heart disease, or cancer can lead to a denial or a much higher premium.
That is why many advisors tell healthy 65-year-olds to at least price a supplement before choosing.
The cheapest option today is not always the cheapest option over 20 years of retirement.
If cash flow is tight, Advantage can be a reasonable bridge, especially if you are healthy and your doctors are in the network.
Just read the summary of benefits carefully and check whether your hospitals and specialists are covered.
If you can afford the monthly premium, a supplement offers more predictable costs and freedom to see doctors nationwide.
For snowbirds and people with ongoing health issues, that flexibility often pays for itself.
Before you decide, call your doctors and ask which plans they accept.
Then run the math on a bad year, not just a good one.
The plan that looks free in January can get expensive by August.
The honest take: Medicare Advantage sells low premiums, and Medigap sells peace of mind, and you are betting on your own health either way.
If you can handle the monthly cost, buy the predictability.
Final Thoughts
If you cannot, go in with your eyes open about the copays and the switching rules.