Health insurance terms decoded: deductible, coinsurance, out-of-pocket maximum

Health insurance documents have their own dialect, and the dialect is doing a lot of work hiding what your actual costs will be. Three terms do most of that work: deductible, coinsurance, and out-of-pocket maximum. Once you can read those three numbers off a plan summary, you can compare any two plans on their own terms.

Deductible

The deductible is the amount you pay out of pocket before insurance starts contributing, in a given plan year.

If your deductible is $3,000:

• The first $3,000 of covered care is on you.
• After that, your insurance starts paying (subject to coinsurance — see below).
• The clock resets on January 1 (for most plans) or the policy's plan year if different.

Some services are typically exempt from the deductible: preventive care under the ACA is generally free regardless, and many plans cover a handful of primary care visits at a flat copay before the deductible.

Deductibles usually come in two flavors: individual and family. The family deductible applies to combined family spending. Either an individual member can hit their individual portion, or the family can hit the aggregate — whichever comes first.

Coinsurance

Coinsurance is the percentage you owe after the deductible is met.

If your coinsurance is 20%:

• After hitting the deductible, insurance pays 80% of the negotiated rate for covered services.
• You pay 20%.
• This continues until you hit your out-of-pocket maximum.

A typical "80/20" plan has 20% coinsurance. "70/30" or "60/40" plans exist and cost less in premium — at the cost of higher exposure on each service.

Don't confuse coinsurance with copay. A copay is a fixed dollar amount you owe per visit ($30 for a specialist, $15 for primary care). Some plans use both — copay for office visits, coinsurance for hospital stays.

Out-of-pocket maximum

This is the most important number on a plan summary and the most often overlooked. The OOP max is the absolute ceiling on what you can pay in a plan year, including deductible, coinsurance, and copays, for in-network covered care.

Once you hit the OOP max:

• Insurance pays 100% of further in-network covered care for the rest of the year.
• The number resets at the start of the next plan year.

In 2026, ACA-compliant plans cap OOP max at $9,200 individual / $18,400 family. Most employer plans set it lower.

What's not counted toward the OOP max: monthly premiums, out-of-network care (unless your plan explicitly counts it), services that aren't covered, and balance billing.

Why these numbers matter together

The trade-off between premium and OOP max is the single most important plan choice. Higher-premium plans typically have lower deductibles, lower coinsurance, and lower OOP maxes. They cost more every month but less in a bad year.

A useful exercise: compute the worst-case annual cost (12 × monthly premium + OOP max) for each plan you're considering. That's the most you'd pay in a serious medical year. Compare that worst case against the best case (12 × premium + no medical care).

For a healthy 30-year-old with no chronic conditions, the best case dominates — a high-deductible plan saves money on premiums and rarely pays out. For a household with predictable chronic care, the worst case dominates — a low-deductible plan caps the exposure.

High-deductible health plans and HSAs

A specific type of plan — a High-Deductible Health Plan (HDHP) — pairs with a Health Savings Account (HSA). The deductible is high (in 2026, at least $1,650 individual / $3,300 family), but the HSA gets three tax benefits:

• Contributions are pre-tax (or tax-deductible if made outside payroll).
• Growth is tax-free.
• Withdrawals for qualified medical expenses are tax-free.

It's the only triple-tax-advantaged account in the US tax code. For a healthy person who can afford to pay routine care out of pocket and let the HSA grow, this is a long-term wealth-building vehicle disguised as a health account.

What "in-network" really means

Every dollar of your deductible and OOP max protection applies only when you use providers in the plan's network. Out-of-network care can be billed at higher rates, the deductible may not apply, and balance billing is permitted in many states. Always verify network status before scheduling non-emergency care.

The clean checklist for comparing plans

When you have plan options to compare:

1. Annual premium (12 × monthly cost).
2. Deductible (individual and family).
3. Coinsurance percentage.
4. OOP maximum (individual and family).
5. Network — are your existing primary care, specialists, and preferred hospital in network?
6. Whether it's HSA-eligible.
7. Whether routine prescriptions and primary care are subject to the deductible or covered before it.

Plans look more similar than they are until you read all seven.