Invoicing and documents
Purchase order (PO)
A purchase order is a legally binding document issued by a buyer to a supplier, authorising a purchase and detailing the exact items, quantities and agreed prices.
What is Purchase order?
A purchase order is your formal request to buy goods or services from a supplier. When the supplier accepts it, the document becomes a legally binding contract. It outlines exactly what you want, how many units you need, the agreed price and the expected delivery date. By issuing a purchase order before a transaction takes place, you protect your business from unexpected price increases and misunderstandings about the order details. In accounting and inventory management, this document is the first step in the purchasing cycle. It forms the foundation for the three-way match, a crucial internal control process where you compare the purchase order against the goods receipt and the final supplier invoice to ensure you only pay for what you actually ordered and received.
How Purchase order works
The purchasing process begins when you identify a need for goods or services and draft a purchase order detailing your requirements. You send this document to your supplier for review. Once the supplier accepts the order, they begin preparing your items for delivery. When the goods arrive, your receiving staff checks the delivery note against the original purchase order to confirm the correct items and quantities arrived. Finally, the supplier sends an invoice for payment. Your accounts payable team then performs a three-way match, comparing the purchase order, the receiving record and the invoice. If all three documents align perfectly, the invoice is approved for payment.
- Buyer identifies a need and drafts the document with item details.
- Buyer sends the formal document to the supplier for approval.
- Supplier accepts the order, creating a legally binding contract.
- Supplier delivers the goods with a corresponding delivery note.
- Buyer compares the received goods against the original order.
- Accounts payable matches the order, receipt and invoice before payment.
Worked example
Gulf Trading LLC needs to restock office supplies. They issue a purchase order to City Stationers for 50 boxes of printer paper at $20 per box and 10 ink cartridges at $45 each. The purchase order lists a subtotal of $1,000 for the paper (50 x $20) and $450 for the ink (10 x $45), resulting in a total order value of $1,450. When City Stationers delivers the goods, Gulf Trading checks the delivery against this $1,450 purchase order. If only 40 boxes of paper arrive, the buyer knows immediately that the delivery is incomplete.
Why it matters for your business
Using purchase orders gives you strict control over your business spending. Without them, employees might order goods informally, leaving you unsure of what was authorised or what price was agreed upon. This lack of documentation often leads to overpaying suppliers or accepting incorrect deliveries. A formal purchase order system prevents these errors and provides a clear audit trail for your accountant. It also helps you manage cash flow by showing exactly what payments are upcoming. Using a system like Paper & Pen, which tracks stock and creates invoices for free forever, makes managing these procurement documents straightforward.
See also
Questions
Common questions
What is the difference between a purchase order and an invoice?
Can a supplier reject a purchase order?
Why is the three-way match important?
Related terms
- Sales order A sales order is an internal document generated by a seller upon receiving a purchase order, confirming the details of the goods or services to be provided to the buyer.
- Invoice An invoice is a commercial document issued by a seller to a buyer, detailing the products or services provided and specifying the amount owed for that transaction.
- Accounts payable Accounts payable is the total amount of short-term debt your business owes to suppliers and vendors for goods or services that you have received but have not yet paid for.
- Delivery note A delivery note is a commercial document accompanying a shipment of goods that lists the description and quantity of items enclosed without displaying their financial value.
- Bill of materials A bill of materials is a comprehensive list of the raw materials, components, and instructions required to construct, manufacture, or repair a finished product.
- Credit note A credit note is a commercial document issued by a seller to a buyer, reducing or cancelling the amount owed on a previously issued invoice due to errors, returns, or damages.