Deductible, coinsurance, out-of-pocket max: what one bill actually costs

Four numbers decide what a US health plan pays and what you pay: the premium, the deductible, the coinsurance or copay, and the out-of-pocket maximum. Your premium is the one you can see every month — and the one that matters least once you actually use care. This page is the arithmetic layer for the other three: how a single bill is split, and how far that split can go before the plan has to cover everything.

The short version

• You pay the plan’s negotiated rate in full until the deductible is met. Then you share costs.
• Once your in-network cost sharing for the year reaches the out-of-pocket maximum, the plan pays 100% of covered in-network care for the rest of the plan year.
• The cap covers essential health benefits. Premiums, balance billing from out-of-network providers, and non-covered services never count toward it — and a plan is not required to count out-of-network spending at all.
• For 2027 the federal ceiling on that cap is $12,000 for self-only coverage and $24,000 for other than self-only coverage — anything covering more than one person — up from $10,600 and $21,200 in 2026.

The order of operations

A bill is not split once. It is split in sequence, and the sequence is what makes two plans with the same coinsurance behave completely differently.

1. The deductible comes first. Until you have met it, you pay the negotiated rate for the service and the plan pays nothing for most services. A “20% coinsurance” plan does not mean you pay 20% from the first dollar — it means you pay everything until the deductible, then 20% after it.
2. Then coinsurance — or a copay. After the deductible, you and the plan split the remainder. Coinsurance is a percentage (80/20 means the plan pays 80%, you pay 20%). A copay is a flat amount, and for office visits and prescriptions it often applies before the deductible rather than after.
3. Then the out-of-pocket maximum. Once your in-network cost sharing reaches the cap, the plan covers 100% of covered in-network benefits for the rest of the plan year.

Two facts decide the real number, and neither is in the headline: what you have already spent toward the deductible and the cap this year, and whether the provider is in network.

Three bills, worked through

Assume a plan with a $2,000 deductible, 20% coinsurance after it, and a $6,000 out-of-pocket maximum — and nothing spent yet this year.

The bill	Toward the deductible	Your coinsurance	You pay	The plan pays
$1,500	$1,500	$0	$1,500	$0
$6,000	$2,000	$800	$2,800	$3,200
$25,000	$2,000	$4,600	$6,000	$19,000

The third row is the cap doing its job. Twenty percent of the $23,000 that remains after the deductible is $4,600, which would bring your total to $6,600 — above the plan’s $6,000 maximum. So you stop at $6,000 and the plan absorbs the remaining $19,000. That single row is why the out-of-pocket maximum, not the deductible, is the number to compare between two plans.

What counts toward the cap — and what does not

The federal definition of cost sharing is narrow, and it is worth reading once rather than assuming. It means what you pay for essential health benefits, and it includes deductibles, coinsurance, copayments and similar charges — but it excludes:

• premiums. Your monthly bill is not cost sharing and never counts toward the cap.
• Balance billing amounts for non-network providers. The amount an out-of-network provider may charge above the allowed amount sits outside the definition entirely.
• Spending on non-covered services. If the plan does not cover it, paying for it does not move you closer to the ceiling.

There is one more gap that catches people out. For a plan that uses a provider network, the rule says out-of-network cost sharing is not required to count toward the annual limit. A plan may count it — many count it up to the in-network rate — but nothing in the rule makes it. So an out-of-network bill, or an in-network visit billed at an out-of-network rate, can leave you paying without ever moving you closer to your maximum.

One scope note: this limit binds non-grandfathered plans. A plan that predates the Affordable Care Act and kept grandfathered status sits outside the rule, and rules for plans sold inside a state’s market can be stricter than the federal floor — insurance is regulated state by state, so what varies by state is the extra protection, not the floor.

The federal ceiling on the cap

A plan may not set its out-of-pocket maximum above a limit that is re-indexed every year against premium growth since 2013. The recent values:

Benefit year	Self-only	Other than self-only
2014 (base)	$6,350	$12,700
2026	$10,600	$21,200
2027	$12,000	$24,000

The 2027 figure is that 2014 base multiplied by the premium adjustment percentage, then rounded down to the next lowest multiple of $50:

$6,350 × 1.8916224814 = $12,011.80 → $12,000

The premium adjustment percentage itself is the measure of how much average per-capita premiums have risen since 2013 — the agency puts it at about 89.2% over the period from 2013 to 2026. That single number drives the cap, and it is why the ceiling rose 13.2% in one year.

What this page does not model

• Copays that bypass the deductible. Common for office visits and prescriptions, and they change the first row of the table above.
• Out-of-network care, balance billing and non-covered services — outside the calculation entirely.
• Cost-sharing reductions. If your income qualifies you for a Silver plan with reduced cost sharing, your real deductible and cap are lower than the plan’s published numbers.
• A whole year. This is one bill at a time. For how the four numbers interact across a year of care, see Premium, Deductible, Copay, Out-of-Pocket Max — and read your plan’s Summary of Benefits and Coverage, which is required to state these figures in a standard format. HealthCare.gov publishes the current plan-year limits and the same list of what the cap excludes.