# Purchase order (PO)

> A purchase order (PO) is the client's formal commercial document authorising the supply of services or goods at agreed terms; its number must appear on reports and invoices for the client to process payment.

- Source: https://amps.global/glossary/purchase-order/
- Type: Glossary
- Published: 2026-09-05
- Tags: operations, finance

## Key facts

- No PO number on the invoice is the most common reason inspection invoices are rejected by client accounts payable
- A PO may cover one job or a period of call-off work; variations need a PO amendment
- Many clients require the PO number on the report as well as the invoice
- The AMPS reporting case study lists PO numbers among the fields filled automatically into reports

Also known as: PO, PO number, client PO.

## In practice

The PO arrives by email, is quoted on the report, then re-typed on the invoice weeks later by someone else. Every re-typing is a chance to get it wrong.

## PO numbers in AMPS

Enter the PO once on the job in AMPS and it is filled automatically into the Word report; when the job is marked ready for invoicing the invoice is created in Xero with the job's references. Email actions let you create jobs or add costs by emailing AMPS.

## Related pages

- [Work order](https://amps.global/glossary/work-order/)
- [Xero](https://amps.global/glossary/xero/)
- [Using the AMPS reporting system](https://amps.global/case-studies/04-reporting-system/)

## Sources

- [Purchase order on Wikipedia](https://en.wikipedia.org/wiki/Purchase_order)