Coinsurance is an expense participation requirement imposed by many medical expense plans; the requirement generally is a specified percentage of all allowable expenses that remain after the insured has paid the deductible and that must be paid by the insured. Most major medical expense policies set the coinsurance amount at 10, 20, or 30 percent of allowable expenses that remain after the insured has paid the deductible amount.
Example. Wendell Ford is covered by a comprehensive major medical expense policy that specifies a $400 calendar-year deductible and a 20 percent coinsurance requirement. In 2010, Wendell incurred $1,000 in allowable expenses.
Analysis. Wendell was responsible for paying the $400 deductible. In addition, he was responsible for paying coinsurance in the amount of 20 percent of the remaining $600, or $120(0.20 x $600). Wendell's total out-of-pocket costs, therefore, were $520($400+$120). The insurer paid the remaining $480($1,000-$520).