Purchase Order Matching Checklist

Before you start

A purchase order is the customer's authorisation to buy, raised before you supply. Many medium and large organisations run 'three-way matching' — they will only pay when the invoice, the purchase order and the goods-received or service-acceptance record all agree. If your invoice does not match the PO, their system holds or rejects it automatically, and no amount of chasing speeds that up until the mismatch is fixed.

Before you invoice, get the PO number and a copy of the PO itself. Never start work on a PO-driven account without one — billing without an authorised PO is one of the most common reasons an invoice is parked. See how to invoice with a purchase order for the wider workflow.

Match the header details

Start at the top of the documents and confirm they agree:

• The PO number is quoted on the invoice exactly as issued
• The supplier name and details match the PO
• The customer entity on the invoice matches the PO's buyer
• The PO is still open and not already fully invoiced
• Any required cost centre or reference is included

A missing or mistyped PO number is enough on its own to bounce an invoice in most accounts-payable systems.

Match the lines and quantities

Now reconcile the detail of the order against what you are billing:

1. Check each invoice line maps to a PO line
2. Confirm quantities billed do not exceed quantities ordered
3. Confirm unit prices match the PO prices
4. Account for any part-deliveries already invoiced against the PO
5. Confirm the running total does not exceed the PO value
6. Apply GST consistently with how the PO was raised

If you have over-delivered or the price has moved, that is a conversation to have before you invoice, not a surprise to bury in the bill.

Handle mismatches and keep evidence

When something does not line up, resolve it deliberately:

• Ask the customer to raise a PO variation for approved extra scope
• Do not simply invoice over the PO value and hope it clears
• Split a part-shipment into a partial invoice that matches what was delivered
• Keep the PO, delivery note and acceptance record on file
• Note the PO and delivery references on the invoice for traceability

Resolving the mismatch first is far faster than letting the invoice reject and chasing the reason later.

Common mistakes

These are the slips that get PO invoices rejected:

• No PO number — or a mistyped one the system cannot match
• Over-billing the PO — invoicing more than was ordered or approved
• Unapproved extras — billing scope with no PO variation
• Stale PO — invoicing against a PO that is closed or exhausted

Build the PO check into your invoicing routine. Our free invoice tools make it easy to show the PO reference clearly, and if PO mismatches are causing invoices to age in a customer's system, a free debt appraisal can help you unstick them.