Prorating Primary Payments

40.8.6.1 - Prorating Primary Payments (Rev. 11550; Issued: 08-12-22; Effective: 10-13-22; Implementation:10-13-22) The A/B MAC (Part A) prorates the undesignated primary payer's payment for Medicare covered services by applying a ratio of this payment between lab and non-lab charges on the bill to determine what portion of the primary payer's payment is attributable to the non-lab charges. Note, the ratio and payment can be done by sending the claim to the MSPPAY module for payment calculation. NOTE: This ratio is based upon Medicare billed charges and not Medicare's payment under the fee schedule.