Purchase Orders Explained: Types, Process, and Best Practices
A purchase order is the binding commitment you send a supplier. Learn the PO types, the process, and how to avoid common mistakes.
Purchase Orders Explained: Types, Process, and Best Practices
Quick answer: A purchase order (PO) is a buyer-issued document that becomes a binding contract once the supplier accepts it. It states the items, quantities, agreed prices, and terms, and is the control point that links a requisition to receiving and payment.
A purchase order turns an approved requisition into a formal commitment. Once the supplier accepts it, the PO is a contract.
What a PO contains
- Unique PO number
- Line items, quantities, agreed unit prices
- Delivery date and location
- Payment terms
Common PO types
- Standard PO — a one-off order for specific items.
- Blanket PO — an agreement to buy up to a value/quantity over time.
- Contract PO — tied to a negotiated contract with agreed rates.
Best practices
- Never let spend happen without a PO ("no PO, no pay").
- Match every PO to a requisition and, later, to a goods receipt and invoice.
- Keep PO numbers unique and traceable.
POs are only as strong as the matching behind them — pair them with three-way matching and a procure-to-pay flow.
Related guides
Frequently asked questions
- What is a purchase order?
- A purchase order is a document a buyer sends a supplier that lists the items, quantities, prices, and terms of a purchase. It becomes a legally binding contract once the supplier accepts it.
- What is the difference between a standard PO and a blanket PO?
- A standard PO covers a single, specific order. A blanket PO is a standing agreement to buy up to an agreed value or quantity over a period, with individual releases drawn against it.
- What does 'no PO, no pay' mean?
- It is a policy where finance will not pay an invoice unless it references a valid, approved purchase order. It prevents unauthorised (maverick) spend and enforces the approval process.