Coinsurance is a percentage of the cost of a health care service, and it’s what you pay once you meet your deductible. A common coinsurance amount is 20%, but the cost-sharing percentages could be anything.
If your doctor visit costs $100 and you’ve met your deductible, your coinsurance payment of 20% would be $20 out-of-pocket. Your insurance would then pay the rest of the allowed amount ($80) for covered health care services.