Document types

Purchase order (PO)

A purchase order (PO) is a buyer-issued document that authorises a supplier to provide specific goods or services at agreed prices and terms, and serves as the buyer's internal reference that accounts payable teams match against the supplier's invoice before paying it.

Applies in: Global

The PO is the buyer's side of the transaction. Procurement or a budget owner inside the buyer raises a PO before any work happens, which authorises the spend and creates a number the supplier should quote on every invoice that follows. When the supplier's invoice arrives, accounts payable matches the invoice against the PO and (in most enterprises) the receiving document. This is the three-way match.

If the PO number is missing or wrong, the invoice usually gets held. AP cannot match it, the budget owner has not authorised the spend in the system, and the invoice sits in a review queue until someone chases it down. Suppliers who do not put the PO number on the invoice are often surprised by how long this delays payment, even when the underlying work is fully agreed.

PO formats vary by buyer. Some are short numeric strings, some include the requesting cost centre, some are alphanumeric with year prefixes. Larger buyers run formal procurement systems (SAP Ariba, Coupa, Oracle) that generate POs; smaller buyers may issue a PO by email or skip the PO step entirely for low-value or recurring spend.

Common questions about Purchase order

Do I need a PO to send an invoice?
Not always. Smaller buyers, especially those not running a formal procurement system, will pay invoices without a PO. Larger and public-sector buyers usually require one and will hold an invoice that arrives without it. The right move is to ask before the work starts: do you raise a PO, and if so, what number should I put on the invoice.
What happens if I send an invoice without a PO number?
At a typical enterprise, the invoice gets parked in an exception queue. AP cannot match it without the PO, so they email the requester or the supplier to find the PO. Resolution time is often measured in weeks, not days. The simplest fix is to add or amend the PO number on the invoice itself once you have it, rather than sending a replacement invoice.
Who issues a purchase order?
The buyer. PO issuance is a buyer-side control to make sure spend is authorised before it happens. The supplier never issues a PO; the supplier issues the invoice. If a buyer asks you to send a PO, they almost certainly mean a quote or a proforma invoice.

Use JupiterInvoice for Purchase order

Purchase order on a JupiterInvoice invoice is a field, a label, and an audit trail your buyer can act on without an email back-and-forth.

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Related terms

Invoice Quote Proforma invoice Credit note Milestone billing

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