Abstract: A method and system for monitoring and maintaining lines of credit secured by accounts receivable processes payments received from customers of a client so as to generate receipts data, and processes the receipts data so as to increase or decrease a line of credit extended to the client based on a collateral account, the value of which is dependant upon the receipts from the customers of the client and transfers from other accounts of the client. The system basically comprises a lockbox for receiving the payments and generating receipts data, and an invoice maintenance system maintained by a financial institution on behalf of the client for processing the receipts data, and generating both receivables data transmitted to an on-line borrowing and repayment system and update data transmitted to a client.