Purchase order (PO)
The client's internal authorization to buy your work, often carrying the PO number accounts payable requires on your invoice.
See it
What it is
A purchase order is a buyer-issued document authorizing a purchase for a named vendor, amount, currency, and set of goods or services. Large clients often require its PO number on every invoice before accounts payable will process it. The PO is issued to you, not just filed on their side, and its attached terms can bind the deal once you accept it. What it is not is payment, or proof that a transfer is on the way.
Ask whether a PO is required during onboarding, before work starts. Check that the legal vendor name, scope, amount, currency, tax treatment, billing entity, and payment terms match the signed agreement. Then put the exact PO number on the invoice and track the remaining authorized amount as change orders are approved. Accounts payable is running a three-way match: the PO, the receipt confirming the work arrived, and your invoice have to agree on vendor, line, and amount before anyone presses pay. A mismatch on any of the three is why your invoice is sitting somewhere unpaid and unexplained.
Gotcha: 'the PO is coming' can strand an invoice outside the client's payment system for weeks. Do not wait until delivery to discover that procurement never issued it. Also read any terms attached to the PO and resolve conflicts with your contract before accepting the order.
Ask AI for it
Build a purchase-order intake packet for a client using Coupa. Include a checklist for legal vendor name, remit-to address, tax details, service description, SOW reference, amount, currency, tax treatment, service dates, billing contact, payment terms, and the required PO number. Add a reconciliation table comparing those values with the signed agreement and invoice, plus a short email asking procurement to correct any mismatch before work begins. Do not treat verbal budget approval as an issued PO.