Section 419.40 - Payment concepts(a) In addition to the payment rate described in § 419.32 , for each APC group there is a predetermined beneficiary copayment amount as described in § 419.41(a) . The Medicare program payment amount for each APC group is calculated by applying the program payment percentage as described in § 419.41(b) .(b) For purposes of this section-(1) Coinsurance percentage is calculated as the difference between the program payment percentage and 100 percent. The coinsurance percentage in any year is thus defined for each APC group as the greater of the following: the ratio of the APC group unadjusted copayment amount to the annual APC group payment rate, or 20 percent.(2) Program payment percentage is calculated as the lower of the following: the ratio of the APC group payment rate minus the APC group unadjusted copayment amount, to the APC group payment rate, or 80 percent.(3) Unadjusted copayment amount is calculated as 20 percent of the wage-adjusted national median of charges for services within an APC group furnished during 1996, updated to 1999 using an actuarial projection of charge increases for hospital outpatient department services during the period 1996 to 1999.(c)Limitation of copayment amount to inpatient hospital deductible amount. The copayment amount for a procedure performed in a year cannot exceed the amount of the inpatient hospital deductible established under section 1813(b) of the Act for that year. 66 FR 59922 , Nov. 30, 2001