Coinsurance refers to money that an individual is required to pay for services, after a deductible has been paid. Coinsurance is often specified by a percentage. For example, the insured pays 20 percent toward the charges for a service and the employer or insurance company pays 80 percent. After the insured has paid the deductible, he’s responsible for a percentage of the costs, specified by the coinsurance split (80/20, 90/10, and 70/30 are common coinsurance splits, with the insured paying the smaller percentage and the carrier paying the higher percentage). That remains the case until the out-of-pocket maximum (OOMP) for the year is reached. At that point, the insurance company starts to pay 100 percent of covered claims until the end of the year.