The LeaseWave® AP system, in combination with the back-end lease management system, allows for the comprehensive management of vendors. Using this as the basis, the system allows for the complete management of vendor invoices. Vendor invoices can be input manually or fed into the system electronically through standard electronic formats or through EDI sources. Once established in the invoice management system, invoices can be routed through the workflow management system for approval of payment. Invoices can be combined in various ways, including across a customer or a vendor, and can be grouped together for combined-approval in the workflow management system. Nuances within an invoice, such as short-paying a vendor, based on undelivered or malfunctioning assets, volume discounts, vendor credit, etc. can also be accommodated. Once approved, check requests can be made in order to process payment on the invoices.