October 5, 2026

Health insurance can feel like a contract written in a second language. You pay every month, yet you still get bills full of terms like deductible and coinsurance.

This guide answers a basic question: how does health insurance work in the US? You'll learn what you pay to keep coverage, what you pay when you get care, where your costs stop, and why networks and approvals matter.

The definitions come from HealthCare.gov, the federal insurance site. Your own plan's details are in its Summary of Benefits and Coverage.

How health insurance works: the short version

Health insurance is a deal between you and an insurer. You pay a monthly premium. When you get covered care, you pay part of the bill through your deductible, copays and coinsurance, and the plan pays the rest. Once your share for the year reaches a cap called the out-of-pocket maximum, the plan pays 100% of covered, in-network care for the rest of the plan year.

Two other rules shape every bill. Your plan pays the most when you use doctors in its network, and some services need the insurer's approval before you get them.

Most working Americans get coverage through an employer. In the 2025 KFF Employer Health Benefits Survey, 88% of covered workers with single coverage were in a plan with a general annual deductible.

Premiums: what you pay to stay covered

A premium is the amount you pay for your health insurance every month. You pay it whether or not you see a doctor. If your coverage comes through work, it's usually taken out of your paycheck.

The premium doesn't count toward your deductible or your out-of-pocket maximum.

When you compare plans, the premium is only half of how health insurance works on your budget. Plans with lower monthly premiums generally have higher deductibles, and plans with higher premiums usually have lower ones. If you expect surgery or ongoing treatment this year, a higher premium with a lower deductible can cost you less overall.

Your deductible: the amount you pay first

A deductible is the amount you pay for covered health care services before your plan starts to pay. HealthCare.gov's example: with a $2,000 deductible, you pay the first $2,000 of covered services yourself.

The deductible usually resets each plan year. Family plans often have both a per-person and a family deductible.

Some exceptions work in your favor. Marketplace plans cover certain preventive services such as screenings and immunizations without a copay or coinsurance when you use an in-network provider, even before you meet your deductible. Many plans also cover some office visits with a copay before the deductible.

The deductible is often the part of how health insurance works that hits hardest. KFF found the average deductible for single coverage was $1,886 in 2025 among workers whose plans have one, up from $1,320 in 2015.

Copays and coinsurance: your share after the deductible

After you meet your deductible, you still share costs with your plan in one of two ways.

A copayment is a fixed amount, such as $20, for a covered service like an office visit. Coinsurance is a percentage, such as 20%, of the cost of a covered service.

Both are figured from the plan's allowed amount, the most the plan will pay for a covered service. Using HealthCare.gov's example, if the allowed amount for an office visit is $100 and you have 20% coinsurance, you pay $20 after your deductible and the plan pays the rest. If you haven't met your deductible yet, you pay the whole $100.

Copays and coinsurance for covered, in-network care count toward your out-of-pocket maximum. Whether a copay also counts toward the deductible varies by plan.

The out-of-pocket maximum: where your costs stop

The out-of-pocket maximum is the most you have to pay for covered services in a plan year. After you spend that much on deductibles, copays and coinsurance for in-network care, your plan pays 100% of covered benefits.

Marketplace plans have a federal ceiling on that limit. For the 2026 plan year, it's $10,600 for an individual and $21,200 for a family. For 2027, HealthCare.gov lists $12,000 and $24,000. Many plans set their limit lower.

This cap is what keeps how health insurance works predictable in a bad year. A few costs never count toward it:

• your monthly premiums
• services your plan doesn't cover
• out-of-network care
• charges above the plan's allowed amount

How it adds up: an example

Here's how health insurance works on one large bill. These are round, made-up numbers for illustration, not real prices.

Say your plan has a $3,000 deductible, 20% coinsurance and a $6,000 out-of-pocket maximum, and you have an in-network procedure with an allowed amount of $12,000.

• You pay the first $3,000, your deductible.
• On the remaining $9,000, you pay 20% coinsurance, or $1,800.
• Your total is $4,800, and the plan pays $7,200.

You'd have $1,200 left before your $6,000 cap. If you needed more in-network care that year, you'd pay coinsurance until you hit $6,000, and the plan would pay 100% after that.

Networks and plan types

A network is the group of facilities, providers and suppliers your insurer has contracted with. Out-of-network care can cost far more and doesn't count toward your out-of-pocket maximum.

Your plan type sets the network rules. According to HealthCare.gov's guide to health insurance plan types:

• An HMO usually covers only doctors who work for or contract with the HMO, except in emergencies.
• A PPO charges you less in network but lets you see out-of-network providers without a referral, at extra cost.
• An EPO covers only in-network care, except in an emergency.
• A POS plan requires a referral from your primary care doctor to see a specialist.

Before surgery, confirm that your surgeon and the facility are both in network, and ask about the anesthesia provider too. Federal No Surprises Act protections also cover unexpected out-of-network bills from emergency care and from some providers at in-network hospitals and surgery centers.

Prior authorization: getting approval first

Some services need your insurer's sign-off before you get them. HealthCare.gov defines preauthorization as a decision by your plan that a service, treatment plan, prescription drug or piece of medical equipment is medically necessary. You may also hear it called prior authorization, prior approval or precertification.

Your doctor's office usually submits the request. Our checklist of questions to ask your surgeon includes asking who handles it.

Approval isn't a promise of payment, which is easy to miss in how health insurance works. Your plan still applies your deductible and coinsurance, and it can deny a claim for other reasons. If that happens, you have the right to appeal the decision, first with your insurer and then through an independent external review.

Use your coverage with confidence

Once you know how health insurance works, your bills get easier to predict. Your premium keeps you covered, your deductible comes first, copays and coinsurance split the cost after that, and the out-of-pocket maximum caps your share.

Before any planned procedure, call your insurer and ask three things: is this doctor in network, does the service need prior authorization, and how much of my deductible is left?

When you're ready, browse doctors on DocFinderPro to find a specialist near you, then confirm with your plan that they're in network.