Drawn as a flow, the purchase order process is six steps in a line. Run in an organisation it is a relay between purchasing, whoever takes deliveries and payables, and things get dropped at the handoffs rather than inside the steps. Marking the handoffs on the diagram is what turns it from a description into something you can improve.
The six steps
A need is requested. It is approved. An order is raised and issued to the supplier. Goods or services arrive and the receipt is recorded. The supplier invoices and the invoice is matched and approved. The order is closed when the quantities reconcile. Each step has an obvious owner except, in most organisations, the fourth.
Handoff one: purchasing to receiving
The order exists and somebody has to record what arrived. Where deliveries are taken by operational staff, this step frequently belongs to nobody, and its absence is the commonest cause of unmatched invoices. It is an ownership conversation, not a software purchase, and it is usually the highest-value change available.
Handoff two: receiving to payables
Payables needs the receipt to complete the match. Where receipts are batched weekly, invoices wait a week for no defensible reason. Recording at the point of delivery removes a delay that costs nothing to remove, and it is why mobile receipting matters more than most purchase order features.
Questions people ask about purchase order process flow
Should the flow include exceptions?
Yes, at least the main branches with owners. A flow showing only the clean path describes the minority of the effort.
Who owns the whole flow?
Somebody senior enough to arbitrate between purchasing and payables, since the friction concentrates at the boundaries.
What should be measured on it?
The elapsed time at each handoff. The delivery-to-receipt gap is usually the largest unmeasured delay in the cycle.