Which type of invoices have no corresponding documents in Ariba?

Non-PO Invoices represent transactions that do not have a prior Purchase Order (PO) associated with them in the SAP Ariba system. This means they are created independently of any specific procurement document that outlines what was ordered or the terms of the purchase. Non-PO Invoices are often used for incidental expenses, services rendered, or goods received that do not require the formalities of a PO.

In contrast, PO Invoices are directly linked to Purchase Orders, Contract Invoices are associated with specific contracts, and Service Invoices are typically related to services that have been agreed upon under a contractual agreement. Since Non-PO Invoices stand alone without these document connections, this makes them unique in the context of invoicing within Ariba. Thus, identifying Non-PO Invoices as the correct answer highlights their distinct nature in the invoice processing workflow.