This update improves automated billing of the customers with complex organizational structures. At its core, update enables the use of the default purchase order (PO) number for each departments, clinic or office as a grouping factor. While schedule can be maintained by the operational team and remain unchanged from the management perspective, billing process can be streamlined and remain fully automated. All interpreting assignments completed for business units with identical default PO are grouped during invoicing process, allowing accounting office to create invoices tailored towards the customer requirements. Default PO can also be used as a cost center. Option is available in account center and can be activated for each individual account.