Direct comparison
Purchase Order vs Invoice: What Each Commits
Purchase order vs invoice: what each document commits the buyer to, what a proper invoice must cite, and how to match PO, receipt and invoice.
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Last updated
How do Purchase order and Invoice compare side by side?
The table below compares Purchase order and Invoice across 10 dimensions, from what it is to when to pick each.
Side-by-side comparison
| Dimension | Purchase order | Invoice |
|---|---|---|
| What it is | A buyer’s order. A purchase order specifies the quantity of supplies or scope of work and is generally issued on a fixed-price basis (FAR 13.302-1). | The seller’s payment document. Under FAR 32.905(a), payment is based on receipt of a proper invoice and satisfactory contract performance. |
| Who issues it and when | The buyer, before delivery. The order must contain a determinable delivery date (FAR 13.302-1). | The seller, after supplies are shipped or delivered, as the request that payment be made (FAR 32.905(a)). |
| What it must carry | Quantity or scope, a determinable delivery date, f.o.b. destination for US deliveries (with stated exceptions), and any trade or prompt-payment discounts offered (FAR 13.302-1). | Seller name and address, invoice date and number, the contract number or other authorization plus the order number and line item number, description, quantity, unit of measure, unit price, extended price, shipping and payment terms (FAR 32.905(b)(1)). |
| How it ties to the other document | It is the origin document. The invoice points back to it by order number and line item. | It must cite the order number and line item, so each invoiced line can be matched to the order line (FAR 32.905(b)(1)). |
| What it commits the buyer to | Under the UCC Article 2 general rule for goods, an order for prompt or current shipment invites acceptance by a prompt promise to ship or by shipment, so the PO is where the offer and its terms sit (UCC 2-206(1)(b)). Outcomes depend on the contract and state law. | A request for payment for what was supplied. Payment is supported by satisfactory performance and by a receiving report or other record authorizing payment (FAR 32.905(a), (c)). |
| Where terms are fixed | In the purchase order and any terms it incorporates; see the linked guide on purchase order terms and conditions. | The invoice repeats shipping and payment terms (FAR 32.905(b)(1)); it identifies the contract or authorization rather than replacing it. |
| The receiving record | Inspection and acceptance should generally be at destination, and receiving reports are to be completed immediately upon receipt and acceptance of supplies (FAR 13.302-1). | All invoice payments must be supported by a receiving report or other documentation authorizing payment (FAR 32.905(c)). |
| What the receiving record shows | Minimum content in the FAR example: contract number or authorization, description of supplies delivered, quantities received and accepted, dates of delivery and acceptance, and the name, title and contact of the responsible official (FAR 32.905(c)). | Matching the PO, the receiving record and the invoice ties the quantity ordered, the quantity accepted and the quantity billed together. |
| Scope of these rules | The FAR sections describe federal government buying. They are a documented example of what these records contain, not a rule for private clinics or resellers. | Same caveat: a private supplier’s invoice and a private buyer’s PO follow the agreement between the parties. |
| When to pick each | Use the PO to place the order and fix quantity, delivery date and terms before goods ship. It is not interchangeable with an invoice. | Use the invoice as the document you pay against after delivery, checked against the PO and the receiving record. It is not an order. |
Sources
- acquisition.gov FAR 13.302-1 (read 2026-11-03)
- Cornell LII UCC 2-206 (read 2026-11-03)
- acquisition.gov FAR 32.905 (read 2026-11-03)
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Common questions
Common questions about Purchase order vs Invoice
What is the difference in purchase order vs invoice?
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A PO is the buyer’s order, issued before delivery with quantity, delivery date and terms (FAR 13.302-1). An invoice is the seller’s request for payment after supply, and a proper invoice carries the order number, line items, quantities and prices (FAR 32.905(b)(1)). The PO is the order; the invoice asks for payment.
Which one applies to a clinic or reseller account?
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Both, at different points: the PO when the account places an order and the invoice when the supplier bills for it. Exact requirements come from the agreement between the buyer and supplier; the FAR sections cited are a federal example of what the records contain.
What does each cost or commit the buyer to?
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The PO is an offer: under the UCC Article 2 general rule an order for prompt or current shipment invites acceptance by a promise to ship or by shipment (UCC 2-206(1)(b)), subject to the contract and state law. The invoice asks for payment of what was supplied; in the FAR example payment is supported by satisfactory performance and a receiving report.
How do I choose between them?
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You do not choose one over the other. Issue the PO to order, keep a receiving record when goods arrive, and pay the invoice once its order number, quantities and line items match the PO and the receiving record.
What is PO vs invoice matching?
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It is checking an invoice against the purchase order and the record of what was received. The FAR example requires invoices to cite the order and line item and requires payments to be supported by a receiving report (FAR 32.905(b)(1), (c)).
