The percentage of costs of a covered health care service you pay (20%, for example) after you've paid your deductible.Let's say your health insurance plan's allowed amountThe maximum amount a plan will pay for a covered health care service. May also be called “eligible expense,” “payment allowance,” or “negotiated rate.”Refer to glossary for more details. for an office visit is $100 and your coinsurance is 20%.If you've paid your deductibleThe amount you pay for covered health care services before your insurance plan starts to pay. With a $2,000 deductible, for example, you pay the first $2,000 of covered services yourself.Refer to glossary for more details.: You pay 20% of $100, or $20. The insurance company pays the rest.If you haven't met your deductible: You pay the full allowed amount, $100.Example of coinsurance with high medical costsLet's say the following amounts apply to your plan and you need a lot of treatment for a serious condition. Allowable costs are $12,000.Deductible: $3,000Coinsurance: 20%Out-of-pocket maximum: $6,850You'd pay all of the first $3,000 (your deductible).You'll pay 20% of the remaining $9,000, or $1,800 (your coinsurance).So your total out-of-pocket costs would be $4,800 — your $3,000 deductible plus your $1,800 coinsurance.If your total out-of-pocket costs reach $6,850, you'd pay only that amount, including your deductible and coinsurance. The insurance company would pay for all covered services for the rest of your plan year.Generally speaking, plans with low monthly premiumsThe amount you pay for your health insurance every month. In addition to your premium, you usually have to pay other costs for your health care, including a deductible, copayments, and coinsurance. If you have a Marketplace health plan, you may be able to lower your costs with a premium tax credit.Refer to glossary for more details. have higher coinsurance, and plans with higher monthly premiums have lower coinsurance.Related contentLearn about deductiblesThe amount you pay for covered health care services before your insurance plan starts to pay. With a $2,000 deductible, for example, you pay the first $2,000 of covered services yourself.Refer to glossary for more details.Learn about allowed amountsThe maximum amount a plan will pay for a covered health care service. May also be called “eligible expense,” “payment allowance,” or “negotiated rate.”Refer to glossary for more details.Learn about out-of-pocket maximumsThe most you have to pay for covered services in a plan year. After you spend this amount on deductibles, copayments, and coinsurance for in-network care and services, your health plan pays 100% of the costs of covered benefits.Refer to glossary for more details.Learn how deductibles and coinsurance affect your total costs of care