The short answer
Here's a fact that surprises many people: Original Medicare, by itself, has no annual out-of-pocket maximum. There's no cap on the 20% coinsurance and deductibles you could owe in a serious health year. That's very different from employer plans and ACA plans, which all have an out-of-pocket cap. The way you get a cap on Medicare is by adding coverage.
So the honest answer is: Original Medicare alone doesn't limit your yearly costs, but a Medigap plan or a Medicare Advantage plan does.
How Advantage and Medigap add a limit
Medicare Advantage plans are required to have an annual out-of-pocket maximum for in-network care — once you hit it, the plan covers the rest for the year. A Medigap supplement takes a different route: instead of a cap, it covers most or all of the gaps, so your costs stay low and predictable without needing a cap at all. Our guide to what Medicare Advantage costs in a bad year explains the Advantage cap.
Both approaches solve the same problem — the lack of a cap on Original Medicare — in different ways.
Why this matters
The absence of a cap on Original Medicare is the single strongest reason not to go without either a supplement or an Advantage plan. In a serious year — a cancer diagnosis, a major surgery — the uncapped 20% can reach staggering amounts. Adding coverage is what protects you from that.
If you're weighing going without a supplement, our guide to what Original Medicare costs with no supplement walks through the real risk. Our Medicare Supplement overview covers how Medigap fills the gaps.
Frequently Asked Questions
Does Original Medicare have an out-of-pocket maximum?
No. Original Medicare by itself has no annual cap on what you can owe in coinsurance and deductibles. You add a cap by getting a Medicare Advantage plan or a Medigap supplement.
How do I get an out-of-pocket limit on Medicare?
Medicare Advantage plans include an annual out-of-pocket maximum for in-network care. A Medigap plan instead covers most gaps, keeping your costs low and predictable without needing a cap.
Why does the lack of a cap matter?
In a serious health year, the uncapped 20% coinsurance on Original Medicare can reach very large amounts. That's the main reason to carry either a supplement or an Advantage plan.
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