Methods for managing requests by a medical services provider for payment from a payer are described. In one embodiment, claims are aggregated into a single file and submitted for payment electronically. If a file level rejection occurs, rejected claims are removed and the single file reformed and resubmitted. This is repeated as necessary until the file is accepted. In another embodiment, claims are assigned first unique identifiers and line items in claims are assigned second unique identifiers. The unique identifiers are used to track every transaction. In another embodiment, an explanation of benefits relating to a claim is received and processed. Copayments are reallocated to line items according to the explanation of benefits. Writeoffs and transfers to next payers are performed automatically according to adjudication codes in the explanation of benefits.