A non-PO invoice is a supplier invoice that arrives without a corresponding purchase order. Nothing was committed in advance, so there is no approved quantity and no approved price to compare the invoice against. It is the structural blind spot of accounts payable control.
Four categories account for nearly all of them, and only the last one is a process failure:
- recurring services such as utilities, rent, insurance and subscriptions, governed by a contract rather than an order
- professional services where the deliverable and the effort are defined as work proceeds
- urgent purchases made outside the normal cycle to avoid a stoppage
- maverick buying, where someone simply ordered without raising a requisition
Their share is usually underestimated. In many mid-sized companies non-PO invoices represent a minority of invoice value but a substantial share of invoice count, and in services-heavy businesses they can be the majority of both.
Three-way matching cannot be applied to them, and pretending otherwise is the common mistake. An invoice with no order and no receipt has only one document to check, so a control designed around three documents has nothing to compare. The realistic answer is not to force a retroactive PO but to substitute a different reference.
That reference is the contract. Phacet's contract data extraction agent structures the agreed rates, terms and escalation clauses, and the invoice versus contract control agent checks each non-PO invoice against them before payment. Combined with duplicate invoice detection and cost centre routing, it restores a real control where the PO chain provides none. See internal controls.
