The term coinsurance is normally associated with health insurance plans.  Coinsurance is the sharing of medical expenses when the patient goes outside the list of network providers associated with their medical plan.


Coinsurance typically applies when the patient is enrolled in managed care plans such as health maintenance organizations (HMO), preferred provider organizations (PPO), and point of service (POS) plans.  The payment obligation is usually stated in terms of a percentage of costs.

Coinsurance is commonly applied after a deductible is first satisfied.  Since payment of coinsurance is the responsibility of the policyholder, it is related to other fee sharing terms such as copayment and deductible.


Bill participates in a PMO, and decides to seek medical attention outside of the network of healthcare providers.  Under these conditions, Bill's plan includes a deductible of $1,000 and a coinsurance agreement of 30%.  The cost for the medical care was $2,000.

Bill's out of pocket costs would be calculated as:

$2,000 Total Invoice
-$1,000 Less: Deductible
$1,000 Amount Subject to Coinsurance
-$300 Less: Bill's Obligation at 30%
-$700 Less: Insurance Company's Obligation
$0 Remaining Balance

In the above example, Bill's total out of pocket expense would be the $1,000 deductible plus the $300 coinsurance payment or $1,300.

Related Terms

health maintenance organization, preferred provider organization, point of service, deductible