What is the difference between a copay and coinsurance?

A copay is a fixed dollar amount you pay for a covered service — say $30 for a doctor visit. Coinsurance is a percentage of the cost you pay after meeting your deductible — say 20% of a $500 procedure. Both are forms of cost-sharing built into health insurance plans.

Copays and coinsurance are two different ways health insurance plans share costs with you, the policyholder. Understanding how they work together — alongside your deductible and out-of-pocket maximum — determines what you'll actually pay when you use healthcare. The HealthCare.gov glossary defines all four terms and is the authoritative plain-language reference for marketplace plans.

What is a copay?

A copay (or copayment) is a fixed, predetermined dollar amount you pay for a specific covered service at the time of care — for example, $25 for a primary care visit, $50 for a specialist, or $15 for a generic prescription. Copays are usually the same regardless of the total cost of the service. Many plans apply copays even before your deductible is met for certain categories like primary care visits or prescriptions, though plan designs vary. HealthCare.gov defines copayments as a fixed amount paid for a covered health care service.

What is coinsurance?

Coinsurance is a percentage of a covered service's cost that you pay after you've met your deductible. If your plan has 20% coinsurance and you've already hit your deductible, a $1,000 covered procedure would cost you $200 — the insurer pays $800. Coinsurance continues until you reach your plan's out-of-pocket maximum for the year, at which point the insurer pays 100% of covered costs. HealthCare.gov's coinsurance definition explains this precisely.

Copay: fixed dollar amount per service (e.g., $30 per visit), often applies before or regardless of deductible.
Coinsurance: percentage of costs (e.g., 20%) you pay after meeting your deductible.
Out-of-pocket maximum: once you hit it, the plan pays 100% of covered costs for the rest of the plan year.
Some services use copays; others use coinsurance — check your Summary of Benefits and Coverage (SBC) for specifics.
Preventive services required under the ACA must be covered with no cost-sharing at in-network providers.

How deductibles, copays, and coinsurance work together

A typical sequence: you pay 100% of covered costs until you hit your deductible. After that, you pay coinsurance (a percentage) or copays (fixed fees depending on the service), while the insurer pays the rest. Once your total out-of-pocket spending for the year hits the plan's maximum, the insurer covers 100% of in-network covered services. The HealthCare.gov guide to comparing plans helps consumers evaluate total expected costs — not just premiums — across plans.

Federal definitions

HealthCare.gov defines a copayment as a fixed amount you pay for a covered health care service, usually when you get the service. — HealthCare.gov
Coinsurance is your share of the costs of a covered health care service, calculated as a percent of the allowed amount for the service. — HealthCare.gov
Under the ACA, in-network preventive services must be provided without cost-sharing — no copay, coinsurance, or deductible. — HealthCare.gov

Key takeaways

Copay = fixed dollar amount per covered service; coinsurance = percentage of covered costs after your deductible.
Both are forms of cost-sharing — they reduce what the insurer pays and increase what you pay out of pocket.
Deductible → coinsurance/copays → out-of-pocket maximum: that's the typical sequence in most health plans.
Some services apply copays before the deductible is met; others require you to meet the deductible first.
Always check the Summary of Benefits and Coverage (SBC) your insurer provides — it maps every service to its exact cost-sharing structure.