Purchase Order

The document that authorises a purchase before it happens

A purchase order is issued by the buyer to the seller, confirming exactly what is being bought, at what price, on what terms, and when it is needed.

It runs in the opposite direction to an invoice, and it comes first. That sequence is the whole point — a PO records what was agreed before goods are supplied, which is why disputes about quantity, price or specification largely disappear once a business starts using them.

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Purchase order vs invoice

These are constantly confused, and the distinction is simple once seen side by side.

They should reconcile to each other. The invoice carries the PO number, and the quantities and prices match. Where they do not, someone supplied something that was not ordered — which is exactly the discrepancy the process is designed to surface.

For the other half, see Payment Invoice.

Is a purchase order a contract?

Not on its own. A PO is an offer to buy. It becomes binding when the seller accepts it — by confirming, or in many cases simply by supplying.

That matters practically. If your PO carries terms and conditions and the seller supplies without objecting, those terms generally govern. If the seller responds with their own terms and you accept delivery, theirs may govern instead. This is the “battle of the forms”, and it is decided by whose terms landed last and were accepted — not by who is bigger.

If your terms matter, put them on the PO and reference them explicitly.

What belongs on a purchase order

• PO number — unique and sequential. This is the reference everything else hangs off
• Date of issue
• Buyer details — legal entity name, address, tax registration where relevant
• Supplier details — legal entity name and address
• Delivery address, if different from the buyer’s address
• Line items — description, specification or part number, quantity, unit price, line total
• Subtotal, tax and total
• Currency, stated explicitly for cross-border orders
• Delivery date or required-by date
• Delivery terms — including Incoterms for international orders
• Payment terms — net 30, net 60, on delivery, or as agreed
• Shipping method and who bears the cost
• Terms and conditions — or a reference to where they can be found
• Authorised signature and approver name

The three-way match

The reason finance teams insist on POs. Before an invoice is paid, three documents are checked against each other:

1. The purchase order — what was ordered
2. The goods received note — what actually arrived
3. The invoice — what is being billed

If all three agree, payment proceeds. If they do not, the discrepancy is caught before money leaves rather than after. This single control prevents duplicate payments, quantity errors and a meaningful share of invoice fraud.

It only works if the PO exists first. Raising a PO after receiving the invoice — which happens more often than anyone admits — defeats the purpose entirely.

Types of purchase order

Standard PO. One-off, for a specific order with known quantities and dates.

Blanket PO. Covers repeated supply over a period against an agreed price, with releases drawn down against it. Useful for regular consumables or ongoing services.

Contract PO. References an underlying supply agreement that governs the commercial terms, with the PO handling the specific order.

Planned PO. Quantities and prices agreed, delivery dates confirmed later.

Most small businesses only need the first two.

Numbering, and why it matters

Use a sequential scheme and never reuse a number. Something like PO-2026-0147 — prefix, year, sequence — is enough, and it makes reconciliation and audit straightforward.

Gaps in a PO sequence are a standard audit query. So are duplicate numbers. Neither is difficult to avoid if the numbering is decided once and followed.

An example prompt

Purchase order from Northwind Studio, Jaipur to Apex Print Supplies, Delhi. PO-2026-0147, dated 18 August 2026. Line items: 500 units A4 matte paper 120gsm at ₹42 each; 40 units magenta toner cartridge model TX-220 at ₹1,850 each. GST 18%. Delivery required by 5 September 2026 to the Jaipur workshop address. Payment terms net 30 from invoice date. Approved by Operations Manager.

That produces a complete purchase order with line items, totals, tax and terms laid out properly, in about a minute.

Related documents

• Payment Invoice — the seller’s side of the transaction
• Purchase Agreement — for a sale of goods or assets, a heavier document than a PO
• Demand Letter for Payment — when an invoice goes unpaid
• Independent Contractor Agreement — for services rather than goods
• Financial documents — the full set
• AI Document Analyzer — read a supplier’s terms before accepting them

FAQs

What is a purchase order?

 A document issued by a buyer to a seller authorising a purchase, setting out what is being bought, the quantity, price, delivery date and payment terms.

What is the difference between a purchase order and an invoice? 

A purchase order is issued by the buyer before supply and authorises the purchase. An invoice is issued by the seller after supply and requests payment. The invoice should carry the PO number and match its quantities and prices.

Is a purchase order legally binding? 

Not on its own — it is an offer to buy. It generally becomes binding when the seller accepts it, either by confirming or by supplying the goods.

What is the difference between a purchase order and a purchase agreement?

 A purchase order covers a specific order of goods or services. A purchase agreement is a fuller contract governing a sale, commonly used for assets, property or significant transactions, and covering warranties, conditions and transfer of title.

Do I need a purchase order for every purchase? 

No. Most businesses set a value threshold above which a PO is required, and use them for supplier relationships where authorisation and reconciliation matter. Small incidental purchases are usually handled on receipts.

What should a PO number look like? 

Any sequential scheme works provided numbers are unique and never reused. A format such as PO-2026-0147 combining a prefix, year and sequence is common and makes reconciliation straightforward.

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IndigoEDocs produces AI-assisted drafts. Tax invoice and procurement documentation requirements vary by jurisdiction — confirm what applies to your business with a qualified accountant.