A data processing system for a billing address-based credit watch comprises a central controller with a CPU and a memory operatively connected to the CPU, and a plurality of creditors. The creditors periodically communicate with the central controller and transmit at least one consumer's payment information including the billing address to the central controller. The memory in the central controller contains a program for execution by the CPU for transferring the billing addresses transmitted from different creditors into a pre-defined common format and for combining the payment information from different creditors by matching billing addresses. Then the central controller transmits back to each creditor periodically the combined payment information including, for each billing address, at least one fraud flag when applicable to detect possible identity theft to provide the billing address-based credit watch.