The association of Dollar (Payment) with Data (Remittance) is called as reassociation and it is the Buzz word in the Medical Banking industry..Ok, let me give some idea about 'Medical Banking'
It is the convergence of the traditional Treasury Management activity with that of the Healthcare clearinghouse,mainly the Treasury mgmt activities Viz Lockbox processing,Electronic payment processing or can be simply pointed to Collections.
This is very clearly mentioned in the 835 implementation guide as follows
The 835 is capable of sending health care claim payment remittance data with or without the dollars represented by the data. It is important to facilitate reassociation when the remittance data is sent separately from the monetary amounts. Reassociation requires that both remittance and monetary data contain information that allows a system to match the items received. The provider should have a method to ensure that payment and remittance advice are reconciled in the patient accounting/accounts receivable system.
Two key pieces of information facilitate reassociation — the trace number in the Reassociation Key Segment, TRN02, and the Company ID Number, TRN03. The trace number in conjunction with the company ID number provides a unique number that identifies the transaction.
The two ways of sending payment for health care remittance data are check or Automated Clearing House (ACH). In the case of a payment received by check, the check number is the trace number in TRN02, and the company ID number is in TRN03. When the check is processed, the check number and account information is captured. A table could be required to cross reference the account information from the check to the company ID number received in TRN03. This information should be gathered when the transaction is implemented with the payer. When sending a separate ACH payment, the CCD+ ACH format is used. Using this method, the Reassociation Key Segment in its entirety is contained in the ACH Addenda Record.
