Posts payment to outstanding invoices within the Accounts Receivable system. 4. Reviews reports of amounts due to the City through third-party billing and.In order to ensure that your payments continue to be processed in a timely manner, please complete the attached agreement and follow submission instructions. The Purchasing department provides and coordinates the procurement of goods and services for the County of Riverside to ensure fair and competitive pricing. ISupplier is a convenient vendor self-service option that allows vendors to track payments and check on the status of submitted invoice(s) online. Hey, im also in the payment processing industry. Invoices can either be mailed to PO Box 868, Riverside, CA 92502 or email us. Contract. • Status of all accounts for the current month and the total in the system. • Aging Receivable Report. For contract management including, but not limited to the following: • Invoicing, accounts receivable, processing, or depositing any payments received.