Purchase order vs invoice: a practical comparison
See how purchase orders and invoices move a business transaction from authorization to payment.
A purchase order and an invoice can list the same goods or services, but they usually come from opposite sides of the transaction. The buyer issues the purchase order; the seller issues the invoice.
The purchase order comes first
A purchase order communicates what the buyer authorizes a supplier to provide. It can list agreed products, quantities, prices, delivery details, and internal approval information.
Using unique PO numbers helps a buyer connect approvals, deliveries, supplier invoices, and payments without relying on email history.
- Created by the buyer
- Sent before delivery or performance
- Authorizes a purchase
- Supports internal controls
The invoice requests payment
The seller sends an invoice after reaching the agreed billing point. It requests payment for the goods or services supplied and states the total, due date, and payment instructions.
Quoting the buyer's PO number on the invoice makes matching faster and may prevent payment delays in organizations that require an authorized order reference.
Matching the records
A simple three-way check compares the purchase order, delivery record, and supplier invoice. Differences in quantity, price, or tax can then be investigated before payment.
Small businesses can benefit from the same discipline even without complex procurement software: consistent numbers and connected documents are often enough.
This guide provides general educational information and is not legal, accounting, or tax advice. Requirements vary by country, industry, and transaction.