A patient receives a $800 medical procedure. The patient has an insurance plan with a 70-30 coinsurance and a $200 dollar deductible. In order to properly bill for this procedure, wed first subtract the deductible from the $800, giving us $600. Wed then divide that $600 into portions of 70% and 30%. Under this agreement, wed bill the payer for $420, and wed bill the patient for $180.