Making a purchase order is a minute of clerical work and it decides how much effort the resulting invoice consumes weeks later. Most of the document is bookkeeping. Three checks, done before it is sent, prevent nearly all of the exceptions that orders cause, and all three are cheap now and awkward once invoices are already arriving.
Check the legal entity
Groups bill from entities whose names differ from the trading name you know. An order raised against the wrong one produces invoices that cannot match, and creating a duplicate supplier record to work around it splits history and disables duplicate detection. Confirm the entity once when the supplier is set up.
Check the units of measure
Ordering by case and being invoiced by unit produces a quantity mismatch every time, forever, and it is nobody's error. Agreeing units with the supplier and recording them on the order removes a permanent exception source with one conversation. It is the most common avoidable mismatch in payables.
Check what the price includes
Delivery, packaging and tax, inside or outside the unit price. An order silent about freight will mismatch every invoice that adds it, which looks like a tolerance problem and is an unstated assumption. Being explicit lets tolerance stay tight enough to catch real price movement rather than absorbing everything.
Questions people ask about how to make a purchase order
What must be on the order?
Unique number, date, supplier legal entity, lines with description, quantity, unit and price, delivery address and date, and your payment terms.
Can we change an order after sending it?
Yes, as a dated revision rather than an overwrite, with re-approval above a threshold.
Should we send terms every time?
Yes. Terms on the order are what you rely on when the supplier's invoice states different ones.