P2P stands for procure to pay, and a p2p procurement system is one that covers the whole cycle rather than one end of it. The technical case is straightforward: the order, the receipt and the invoice live in one place, so matching needs no integration. The difficulty is organisational, because it is a change to two departments with different priorities, at the same time.
What one system genuinely buys you
No reconciliation between an ordering system and a payables system, because there is only one record. Exceptions can be routed back to purchasing without leaving it. The open-order report, the accrual and the invoice queue all come from the same data. Where your exceptions are dominated by missing orders and receipts, this addresses the cause directly.
Why the implementations are harder
Two departments must agree on cost centre structures, approval thresholds, supplier records and what a receipt means. Each of those is a small negotiation and together they are most of the project. The technical work is rarely what delays a p2p implementation; the agreements are, and they are best started before any software is chosen.
How to reduce the risk
Clean supplier and cost centre data first, since both departments will fight over it later otherwise. Agree the thresholds and the exception owners on paper before configuring. And stage the rollout, usually orders and receipts first, then invoices, so that each phase delivers something rather than everything landing at once.
Questions people ask about p2p procurement system
Is p2p worth it for a small organisation?
Sometimes, if the seam between ordering and paying is genuinely where your problems are. If they sit inside payables only, a point solution is faster and cheaper.
Who should lead it?
Somebody with authority over both departments, because most decisions are cross-departmental. A project led by one side reliably produces a system the other works around.
What should we do first?
Clean supplier records and agree cost centre structure. Both are unglamorous and both determine how the rest of the project goes.