Definition
A PO number is the unique identifier on a purchase order that a buyer issues before a sale. Suppliers include the PO number on their invoice so the buyer's accounts payable team can match the invoice to the approved order. Invoices without a required PO number are frequently rejected or delayed.
Also called: Purchase order number
PO number in practice
Always ask corporate clients whether they require a PO before starting work, and add a PO number field to your invoice template. If the PO total differs from your invoice, resolve it before invoicing.
Frequently Asked Questions
What if the client did not give me a PO number?
Ask before invoicing. If their process requires one, the invoice will stall until you have it. If they do not use POs, leave the field blank or omit it.