A purchase order (PO) is a document a buyer issues to a seller to authorize a purchase. It lists the items, quantities, agreed prices, and terms of the deal, and usually mirrors a quote the buyer already accepted. Once the seller accepts the PO, it becomes a binding commitment between the two parties.
How it works
The typical flow is quote first, then PO. A buyer requests a quote, reviews it, and if the numbers work, issues a PO that references that quote. The PO carries a unique PO number, the line items, unit and total pricing, delivery details, and payment terms such as Net 30. The seller acknowledges the PO, fulfills it, and later invoices against the same PO number so accounts payable can match the invoice to the original authorization.
Why it matters
For B2B buyers, a PO is often a hard requirement. Procurement teams cannot release payment without one, because it is how they control spend and keep an audit trail. For sellers, an accepted PO is a clear signal to move a deal from proposal to order, and the PO number becomes the reference that ties quote, order, and invoice together.
In Shopify B2B quoting
Native Shopify checkout is not built around formal POs, so merchants selling to businesses often handle them alongside quotes. A common pattern is to treat an accepted quote as the trigger to create an order, then capture the buyer’s PO number on that order for reconciliation. Many buyers also want to pay by PO on terms rather than card, which is where Shopify B2B payment terms come in. See the B2B quoting glossary for related terms like RFQ and Net terms.
Example
A distributor sends a quote for 500 units at an agreed unit price. The buyer’s procurement system generates PO number 4021 referencing that quote and emails it over. The seller accepts, ships, and invoices against PO 4021, and both sides can trace the transaction end to end.