A purchase order is you committing to buy, in writing
It goes the other way round from an invoice: you raise it, you send it to your supplier, and it says what you are ordering and what you have agreed to pay for it.
Once the supplier accepts it, you have a contract. That is the point of it. A phone order for four tonnes of ballast is a conversation nobody can evidence. A numbered PO for four tonnes of ballast at an agreed rate is the document you hold up when six tonnes turn up and the invoice is half as much again as you expected.
Why the PO number has to appear on their invoice
Because without it, nobody in your business can tell whether the invoice is for something anyone actually ordered.
This is the whole reason purchase orders exist. When the invoice arrives carrying the PO number, you can line up three documents: what you ordered, what the delivery note says arrived, and what you are being billed for. If all three agree, pay it. If they do not, you have found the problem before the money went out rather than three months later in a reconciliation.
That is why this PO says on its face that the number must appear on the invoice and on all delivery paperwork. Suppliers who ignore it get their invoice held, and being able to point at the line is what makes that reasonable rather than obstructive.
What to put on a PO
- Your PO number, prominently. One sequence, no gaps, so a missing number is visible.
- Quantities and units that mean something. "Ballast, 4 tonne bulk bags, qty 4" rather than "ballast".
- The agreed price per line. A PO with no prices is a wish list and gives you nothing to challenge an invoice with.
- Where and when it goes. Site address and required date. Most delivery arguments are actually about one of these two.
- Who raised it. So the supplier knows who to ring, and so you know who to ask.
Numbering, and why gaps matter
Use one continuous sequence across the whole business, not one per supplier or one per job.
A single sequence means a gap is a question: was that PO cancelled, or did somebody raise it and never tell anyone? Per-supplier sequences hide that completely. The tool suggests a number with the year in it so orders group by year without you inventing a scheme, and you can override it if your accounts package already owns the numbering.
POs on a construction site
The commercial value of a PO on site is that it stops the "somebody must have ordered it" invoice.
Plant hire is the worst offender: kit stays on site three weeks past when it was needed and the hire invoice arrives for the full period. A PO with an end date on it turns that from an argument about memory into an argument about a document. Same with materials ordered by whoever was on site that morning.
Free, and nothing leaves your device
No account, no email, no watermark, no limit on lines. Your logo and company details come from your branding.
The PDF is generated in your browser, so your supplier list, your rates and your sites never reach a server.
Common questions
What actually is a purchase order?
It is you committing to buy, in writing, before the supplier does any work. Once the supplier accepts it, you have a contract, which is a very different position from a phone order for materials that nobody can evidence later.
Why does the PO number need to be on the supplier's invoice?
So you can line up three documents: what you ordered, what the delivery note says arrived, and what you are being billed for. If all three agree, pay it. If they do not, you find the problem before the money goes out rather than months later in a reconciliation.
What should I include on a purchase order?
Your PO number shown prominently, quantities and units that actually mean something rather than a vague description, the agreed price per line, the site address and required date, and who raised the order so the supplier knows who to contact.
Should I use a separate PO number sequence for each supplier?
No, use one continuous sequence across the whole business. A single sequence means a gap is a question worth asking, whereas per-supplier sequences hide a missing or unauthorised order completely.
How does a purchase order help with plant hire on site?
It stops the "somebody must have ordered it" invoice. Plant hire is the worst offender for kit staying on site weeks past when it was needed, and a PO with an end date on it turns that from an argument about memory into an argument about a document.
Is the purchase order generator free to use?
Yes, with no account, no email and no watermark, and no limit on the number of lines. The PDF is generated in your browser, so your supplier list, rates and sites never reach a server.