Business document
Purchase Order (PO)
The buyer's instruction to supply. It usually forms the contract, it usually attaches the buyer's own terms, and its number is the key that every later document — including your invoice — has to match.
Also called: Order · Customer order · Works order (in some sectors) · Contract order
- Who sends it
- The buyer's purchasing function, or automatically from their MRP or procurement system once a requisition is approved.
- Who receives it
- The supplier's sales or order administration function, who should review it against the quotation before accepting.
- When it is used
- When the buyer decides to proceed. Also issued as amendments when quantity, price or dates change, and as call-offs against a blanket order.
- Does it bind anyone
- High. It is usually either an acceptance of your quotation — forming a contract on your terms — or a counter-offer on the buyer's terms, which you accept by acknowledging it or by starting work. Either way a binding contract normally exists without a signature, which is exactly why it should be read before anyone acts on it.
What it is
A purchase order is the buyer's formal instruction to supply specified goods or services at a specified price by a specified date. It is generated by the buyer's system, usually after an internal approval, and it commits budget on their side.
For the supplier it does two things at once. It normally accepts the quotation and forms the contract — often bringing the buyer's own conditions with it. And it creates the reference number that the buyer's finance systems will use for the rest of the transaction's life.
That second function is underestimated constantly. In any customer large enough to have a shared service centre, the PO number is the join key between three separate records: the approved order, the goods receipt, and your invoice. If those three do not agree, an automated match fails and your invoice stops moving — usually without anybody telling you.
Every field explained — 24 in total
What each field means, a realistic example value, whether you can leave it out, and the thing that goes wrong with it in practice.
| Field | What it means | Example | Needed? |
|---|---|---|---|
| Purchase order number | The buyer's unique reference for this order.Watch out The most consequential string in the whole chain. It must be reproduced exactly — including prefixes, leading zeros and suffixes — on your acknowledgement, packing slip and invoice. A single transposed character turns a routine payment into a silent exception nobody has been assigned to investigate. | 4500-887-2261 | Required |
| Order date | When the order was raised, which is not necessarily when it was sent.Watch out Orders sometimes sit for days between being raised and being sent. If the delivery date is calculated from the order date, you may have lost part of your lead time before you saw it. | 22 March 2026 | Required |
| Revision or amendment number | Whether this supersedes an earlier version of the same order.Watch out Amendments are frequently sent to the wrong person or as an attachment with no covering note. Working from a superseded version is common and produces exactly the mismatch that stops the invoice. | Amendment 2 | Conditional |
| Buyer's legal entity and address | Which company is actually contracting — often not the one you have been talking to.Watch out Groups place orders through different entities in different countries. It changes the tax treatment, the credit exposure and who you would have to pursue for payment. | Northgate Engineering (Holdings) Ltd, Sheffield | Required |
| Supplier name, account number and address | You, as recorded in their system. | Rochdale Precision Ltd, supplier 60214 | Required |
| Reference to the quotation | Which offer this order is accepting.Watch out Frequently absent on repeat business, which leaves the price basis unstated. If it is missing, establish in writing which quotation or price agreement the order is placed under before entering it. | Per your quotation Q-11482 rev 2 | Conditional |
| Line number | The buyer's line reference, used for line-level matching.Watch out Many accounts payable systems match at line level, not order level. Your invoice may need to carry their line numbers as well as their order number. | Line 010 | Required |
| Part number and description | What is being ordered, in the buyer's numbering.Watch out Their part number, not yours. Both need to appear on your documents, because their goods-in and accounts payable both search on theirs. | NG-44821 — Mounting bracket LH | Required |
| Drawing number and revision | The engineering definition the parts must be made to.Watch out Check it against the revision you quoted. A revision change between quote and order is a requote, not a formality — and it is one character on a dense page, so nobody sees it unless they are looking. | NG-44821 rev D | Required |
| Quantity | How many, on this line.Watch out Check it against the price break the price came from. An order for 100 at the 400-off price is wrong even though it matches your quotation exactly. | 400 | Required |
| Unit of measure | Each, kg, metres, hours, thousands.Watch out Ordering in thousands when you priced in units, or metres when you priced per bar, produces errors of a factor of a thousand that pass every visual check because the number looks plausible. | EA (each) | Required |
| Unit price and line value | The price the buyer has approved.Watch out If it differs from your quotation, query it and get an amended order. Never correct it silently — the invoice must match what their approver signed off, in either direction. | £17.20 each, £6,880.00 | Required |
| Currency | The currency of the order. | GBP | Required |
| Required delivery date | When the buyer needs it.Watch out Often generated by the buyer's MRP rather than by a person. Confirm it is achievable before acknowledging it; a date accepted in silence becomes a date you have promised. | 19 April 2026 | Required |
| Delivery schedule | Multiple dates and quantities against one line, on scheduled or blanket orders.Watch out Must be entered as separate lines in your system, never as a note. A schedule typed into a comment field is invisible to planning and will be made and shipped as one batch. | 100 on 19 Apr, 150 on 17 May, 150 on 14 Jun | Conditional |
| Ship-to address | Where the goods go. | Goods-in Bay 4, Northgate Engineering, Sheffield S9 | Required |
| Bill-to address | Where the invoice goes — frequently a different entity in a different country.Watch out Sending the invoice to the buyer or the delivery site instead of the billing address is one of the most common causes of a lost month. | Northgate Shared Services, Kraków, Poland | Required |
| Delivery terms (Incoterms) | Who arranges and pays for transport, and where risk passes.Watch out Check it against what you quoted. Quoting ex-works and receiving an order stating delivered means the freight is now yours and was never priced. | DAP Sheffield (Incoterms 2020) | Required |
| Payment terms | When the buyer intends to pay.Watch out Buyers routinely place orders on their standard terms regardless of what was agreed. If it differs from the quotation, object in the acknowledgement — a term you do not challenge is a term you have accepted. | 60 days from end of month of invoice | Required |
| Tax treatment and registration numbers | VAT or sales tax status, registration numbers, reverse charge indicators. | VAT GB 412 8874 09 | Conditional |
| Quality and certification requirements | What must accompany the delivery.Watch out Belongs on the order line as a flag that blocks despatch. Perfect parts delivered without the paperwork are rejected at goods-in and pay freight both ways. | Certificate of conformity required with each delivery | Conditional |
| Packaging, labelling and delivery instructions | How the goods must arrive and how the delivery is booked. | Max 50 per carton; label per PL-07; slot booked 48h ahead via portal | Conditional |
| Terms and conditions of purchase | The buyer's contractual terms, attached or referenced.Watch out This is how liquidated damages, extended warranties, audit rights and liability caps enter the contract. They will apply unless you object, in writing, before you start work. | Subject to Northgate Conditions of Purchase rev 7 | Required |
| Authorised by | The person or approval level that released the order.Watch out An order emailed by someone without release authority may not be payable. On large first orders it is worth checking that the approval exists in their system. | Approved: M. Trescothick, Purchasing Manager | Required |
A filled-in example
Realistic values throughout — the sort of document that would actually pass through a business.
Purchase Order 4500-887-2261 — Northgate Engineering
- PO number
- 4500-887-2261
- Order date
- 22 March 2026
- Supplier
- Rochdale Precision Ltd (60214)
- Per quotation
- Q-11482 rev 2
- Ship to
- Goods-in Bay 4, Sheffield S9
- Bill to
- Northgate Shared Services, Kraków
- Delivery terms
- EXW Rochdale (Incoterms 2020)
- Payment terms
- 60 days from end of month
| Line | Part / drawing rev | Description | Qty | UoM | Unit price | Required |
|---|---|---|---|---|---|---|
| 010 | NG-44821 rev D | Mounting bracket LH | 400 | EA | £17.20 | 19 Apr 2026 |
| 020 | NG-44822 rev D | Mounting bracket RH | 400 | EA | £17.20 | 19 Apr 2026 |
| 030 | NG-44830 rev A | Spacer, stainless 316 | 1,600 | EA | £2.45 | 19 Apr 2026 |
| 040 | — | Inspection fixture (one-off) | 1 | EA | £2,850.00 | 05 Apr 2026 |
- Order total
- £20,530.00 excluding VAT
- Quality
- CoC required with each delivery
- Conditions
- Subject to Northgate Conditions of Purchase rev 7
- Approved by
- M. Trescothick, Purchasing Manager
What happens next
- 01The supplier reviews the order line by line against the quotation — price, quantity, revision, dates, terms.
- 02Anything that does not match is queried in writing, and an amended order is requested rather than corrected internally.
- 03An order acknowledgement is issued confirming what will be supplied, by when, and on whose terms.
- 04The order is entered as a sales order, becoming demand for planning and an entry in the order book.
- 05On delivery, the buyer posts a goods receipt against this PO number; the invoice is then matched against both.
Where it appears in the chain
- Negotiation and revised offersThe period between the quote going out and the order arriving, when price, quantity, lead time and terms all move — and where concessions get given that nobody downstream ever hears about.
- Receiving the customer's purchase orderThe customer commits. Before anyone celebrates, the purchase order has to be read line by line against the quotation it claims to accept — because the two disagree more often than anyone expects.
- Order entryTyping the accepted order into the system that everything downstream reads from. Every error made here is repeated by production, despatch and invoicing, and is discovered by the customer.
Common mistakes
MistakeEntering the order without reading it
Why it happens: It is good news and everyone wants it in the system. The mismatches surface later, discovered by production or by accounts receivable.
What to do instead: A fixed six-point check before entry — price, quantity, revision, date, terms, credit. Five minutes, and it prevents most downstream disputes.
MistakeMissing that the drawing revision changed
Why it happens: One character in a dense table, and the part number is identical.
What to do instead: Make revision a mandatory comparison against the quotation, and stop the order when it differs. A revision change is a requote.
MistakeWorking from a superseded amendment
Why it happens: Amendments arrive as attachments to short emails, sometimes to the wrong person.
What to do instead: Check for a revision or amendment number on every order, and confirm you hold the latest before entry.
MistakeAccepting the buyer's terms by silence
Why it happens: The conditions are referenced on the order and attached as a separate PDF nobody opens.
What to do instead: Acknowledge every order on your own conditions and object explicitly to any specific clause you do not accept — before starting work, not after.
MistakeTreating a blanket order as immediate demand
Why it happens: The order shows a total quantity, and the schedule sits in a separate section or an attachment.
What to do instead: Enter each call-off as its own line with its own date. Making the whole contract quantity at once ties up cash and risks obsolescence on a revision change.
MistakeNot checking credit before accepting
Why it happens: Sales and credit control work in different systems and the order is urgent.
What to do instead: Credit check is part of order acceptance, not part of invoicing. Discovering the account is on stop after the material is cut is the expensive version.
Terminology
- Three-way match
- The buyer's automated check that purchase order, goods receipt and invoice all agree before payment is released.
- Blanket order
- An order covering an agreed total quantity over a period, against which individual deliveries are called off.
- Call-off
- An individual release against a blanket order or schedule agreement.
- Requisition
- The internal request that precedes a purchase order and triggers the buyer's approval process.
- Counter-offer
- An order that changes the terms of the quotation it responds to, and therefore requires acceptance rather than granting it.
- Goods receipt
- The buyer's record that the goods arrived and in what quantity. The middle leg of the three-way match.
Common questions
›Is a purchase order a contract?
It is usually the acceptance that forms one, or a counter-offer that you accept by acknowledging it or starting work. In practice a binding contract normally exists without either party signing anything, which is why reviewing the order before acting on it is the whole point of the step.
›Why is the PO number so important?
Because it is the key the customer's accounts payable system matches on. Large buyers run automated three-way matching, and an invoice carrying a PO number that does not exist in their system drops into an exceptions queue — reviewed weekly, monthly, or when someone chases. Nobody notifies you. It is the most common reason a correct invoice goes unpaid.
›What should you do if the purchase order does not match your quotation?
Query it in writing and ask for an amended order before entering it. This applies even when the error is in your favour, because the invoice has to match what the customer's approver signed off, and an invoice for more than the approved order fails just as hard as one for less.
›Do you have to acknowledge a purchase order?
Not legally, in most cases, but it is the mechanism that establishes your delivery date and your conditions as the ones that govern. Suppliers who skip it are consistently the ones arguing later about what was promised and whose terms applied.
›What is the difference between a purchase order and a sales order?
The same agreement seen from each side. The purchase order is the customer's document instructing you to supply; the sales order is your record of what you have agreed to supply. Order entry translates one into the other, and any drift between them becomes a dispute.
›Can you start work before the purchase order arrives?
Commercially, sometimes you must. Contractually, you are exposed — there is nothing to enforce and nothing to invoice against. If material has to be committed on a verbal instruction, get it in writing by email at minimum and treat the exposure as an approval decision rather than a favour.
Tools for this
Downloadable, self-contained, and yours to keep — they run in a browser with no account and no data leaving your machine.
- Purchase Order TrackerFreeTrack purchase orders from raising to invoice: committed spend by cost centre, overdue deliveries, goods received but not invoiced, and a three-way match that catches duplicate and inflated supplier invoices. Runs entirely in your browser — nothing is uploaded.
- Order Backlog DashboardProSee your open order book as money: backlog value by due week, overdue and at-risk orders, customer concentration, aging and where the value sits in production. Runs entirely in your browser — nothing is uploaded.
Reviewed 2026-08-15. Nothing here is legal, tax or accounting advice — the mandatory content of commercial and tax documents varies by jurisdiction, so confirm the specifics for where you trade.