What a purchase order actually does
Use a PO to make the requested purchase and its authorization traceable. Check the issuer, supplier, scope, amounts, delivery instructions and terms before relying on it. This guide does not determine the legal effect of a particular purchase order.
A buyer may use an internal approval process before issuing a PO. If the buyer requires its PO reference on the invoice, reproduce that reference accurately alongside your own invoice number. Do not assume every buyer uses the same process or rejects every invoice without a PO.
What goes on a purchase order
Use this practical checklist to prepare or check an order, not as a universal statutory list of mandatory fields:
The buyer issues the PO; the supplier may later quote the buyer's reference on its invoice. Check the issuer and recipient instead of copying the From and To positions from an invoice. Reproduce the customer-issued PO number rather than inventing one.
- PO reference — use the buyer-issued reference where the buyer requires it.
- Date issued — and, separately, the date the goods or services are needed.
- Buyer details — company name, address, and the person who authorised it.
- Bill To and Ship To — often different addresses. Head office pays; the site takes delivery.
- Seller (vendor) details — the business the order is going to.
- Line items — description, quantity, unit price, line total. Specific enough that the seller can't reasonably send the wrong thing.
- Subtotal, applicable tax and total — check the amounts and currency for this order.
- Delivery date and method — when it's needed and how it's getting there.
- Payment terms — Net 30, Net 15, on delivery, whatever was agreed.
- Authorisation — a name, and on paper POs a signature.
Purchase order format: choose the file you can use
For a reusable layout, visit the purchase order template. Choose the document and format that suit the purchase, then check the fields, calculations and tax treatment before use. This guide does not itself provide a download.
Purchase order sample: standard or blanket?
For a specific order, record the items, quantities and requested delivery. For repeat purchases, ask the buyer whether one order reference covers several releases or invoices and how changes are approved. North Tyneside Council, for example, distinguishes standard and call-off orders; its call-off orders can involve multiple invoices. That is one buyer's practice, not a universal PO taxonomy. Do not infer the order type or billing rights solely from a twelve-month reference.
Types of purchase order you’ll come across
A standard purchase order records one defined purchase with its items, quantities, prices and requested delivery. A blanket or call-off arrangement can provide one reference for repeat releases under the buyer’s stated process. A planned order can record expected quantities or timing before each release is finalized. These labels describe common workflow choices; the buyer’s document and instructions define what its reference covers.
Choose the format by the task the record needs to support. Use a standard order when the quantity and delivery are known, and use a repeat-purchase format only when the buyer has established how releases, limits and changes are recorded. Keep each release or invoice connected to the original reference without treating an estimate as a committed quantity.
Purchase orders, delivery notes and invoices — the paper trail
Keep the PO with the delivery or service record and the invoice. Compare the description, quantity, price and amount currently billable. Keep the invoice's own reference as well as the customer's required PO number.
Illustrative example excluding tax and fees: an order for 40 units at $12 totals $480. The receiving record lists 32 units, or $384 at that unit price, with 8 units outstanding. Check the agreement before deciding what is currently billable. A mismatch calls for explanation or correction; it does not prove why invoices in general are delayed.
If you only remember one line: a purchase order is a request to buy, an invoice is a request to be paid. Purchase order vs invoice covers the differences in full.
The three records can carry different dates and references while describing one purchase. The PO identifies what the buyer ordered, the delivery or service record shows what was received or completed, and the invoice states what the seller is billing. Keeping all three references visible makes a partial delivery or revised quantity easier to explain.
When you don't need a purchase order
Check the buyer's actual process. Some purchases proceed under another authorization record, but an accepted quote does not automatically waive a customer's PO requirement. Resolve a missing reference with the buyer rather than inventing one or assuming an exception.
If you are the supplier, ask the commissioning or purchasing contact for the correct reference and where it belongs before submitting your invoice. Keep your invoice number too.
Haringey Council's published supplier policy provides one example: it requires a valid PO issued in advance and correctly quoted on the invoice. Suppliers without a reference are directed to the officer who commissioned the work. The policy lists exceptions, including some rent, rates, grants and statutory payments; its rules do not apply to every customer.