The total allowed charges on the claim (the sum of line item allowed charges).
Sum of all the line LINE_NCH_PMT_AMT values for the claim.
Medicare payments are described in detail in a series of Medicare Payment Advisory Commission (MedPAC) documents called “Payment Basics” (see: http://www.medpac.gov/payment_basics.cfm).
Also in the Medicare Learning Network (MLN) “Payment System Fact Sheet Series” (see http://www.cms.gov/Outreach-and-Education/Medicare-Learning-NetworkMLN/MLNProducts/MLN-Publications.html).
Source: NCH QA Process