Your share of the costs of a covered health care service, given as a percent (for example, 20%) of the allowed amount for the service. For any particular doctor's visit, medicine, or procedure, you pay coinsurance plus any deductibles you owe.


If the health insurance or plan’s allowed amount for an office visit is $100 and you’ve met your deductible, your coinsurance payment of 20% would be $20. The health insurance or plan pays the rest of the allowed amount.