Businesses often require down payments from customers to ensure orders are fulfilled. In SAP Business One, down payment requests or invoices can be issued to customers or received from vendors. After payment is received, it is deducted from the final invoice amount. The process involves creating a down payment request or invoice, receiving payment, and creating a regular invoice to which the down payment is applied. This ensures commitments are met while properly accounting for down payments in the order fulfillment lifecycle.