The invoice is a legally binding document. When an invoice is received, the posting is made to the related customer accounts in the accounting system. If a delivery did not precede the invoice and you sell the warehouse items, inventory quantities are also updated accordingly when you issue the invoice.

If you create an invoice without reference to the delivery, the system automatically posts changes to the inventory. In other words, if a delivery already exists for the transaction and you create an invoice without reference to this delivery, errors can occur in inventory management because the delivery quantity is posted twice in the system.

SAP Business One enables you to create an A/R invoice with a zero amount. You can do this when delivering items without a charge, for example, items that are part of a promotion or covered by a service contract.

To access this function, choose  Sales – A/R A/R Invoice .