A supplier sends an invoice with the right company name and a familiar total. That does not establish that the goods were authorised, delivered or billed correctly. The invoice belongs in a chain of records, not on an island.
A purchase order and an invoice can contain similar descriptions while serving different purposes. Understanding who issued each document helps explain what it can prove.
Follow the direction of the documents
Xero’s purchase-order guide distinguishes the buyer’s order from the supplier’s request for payment. It also separates internal purchase requisitions and supplier sales orders. The precise contractual effect depends on the agreement and jurisdiction; these practical labels are not a substitute for legal advice.
The purchase order describes what the buyer intends to purchase under the stated terms. The invoice requests payment. Neither document alone necessarily establishes that every item arrived in acceptable condition.
Compare the line items, not only the total
Use the order, receipt or delivery record and invoice together under the organisation’s procedure. Check quantities, descriptions, prices, taxes, delivery charges and any approved changes. Partial deliveries need particular care because the full order and the current invoice may cover different amounts.
For a fictional example, a workshop orders twelve identical components but receives eight. An invoice for all twelve should prompt a check of the agreed billing arrangement and delivery status, not an automatic payment because the order total matches.
Keep a discrepancy visible until the responsible person resolves it. Do not alter a supplier’s document to make it fit or approve a payment based only on a reassuring phone conversation with an unverified caller.
Preserve the reason for the decision
Record who approved a change, which items remain outstanding and how a correction will be handled. If the supplier issues a revised invoice or credit note, connect it to the original record so the same obligation is not processed twice.
A useful purchasing process makes each document answer its own question: what was authorised, what arrived and what is being requested for payment. When those answers align, the paperwork becomes an operational control rather than a pile of similar-looking forms.