Start with the evidence
Gather the payment evidence and the customer’s remittance details. List the invoice references individually and check whether the stated amounts cover them fully or only in part.
Work through the example
An example payment of USD750 covers EX-201 for USD300 and EX-202 for USD450. The two allocations sum to the received amount; neither invoice should show a separate additional USD750 receipt.
Make the next step clear
Retain the allocation note with the payment reference. If the customer’s breakdown does not add up, leave the difference as an open question rather than spreading it arbitrarily across the documents.
Keep the source context
An invoice record and a customer conversation provide different evidence. Keep original document references stable while adding dated notes about replies and related payments. These guides concern clear administration, not collection tactics or promises of automated money movement.