How to handle invoices that arrive without a purchase order with an AI agent

Sort first, chase second. The agent checks whether the invoice belongs to a category your policy exempts from purchase orders, such as rent or utilities, and routes those for normal approval. For the rest, it finds who ordered the goods, asks them to confirm receipt, and drafts a retrospective requisition for procurement to approve. It never creates a purchase order just to make the invoice match.

What is the problem, and who owns it?

Most purchase-to-pay processes expect a purchase order before an invoice: someone asks, someone approves, an order goes to the supplier, goods arrive, the invoice matches. The flow is explained in what is purchase-to-pay. Invoices that arrive with no order break that chain. Some are expected, because certain spend never goes through ordering. Others mean somebody bought something without approval, and the invoice is the first time finance has heard of it.

The accounts payable lead owns the handling of no-order invoices. The head of procurement owns the exempt list and the policy on retrospective orders. Budget holders confirm and approve spend on their cost centres. The wider finance position is in AI agents for finance: books you can audit.

How does the agent handle them, step by step?

1. Agent, depth 1: confirms there is no order. Many "no order" invoices carry a reference in an unusual place, or quote a contract number instead. It searches open orders for the supplier, amount and description. Evidence: the search and its result.
2. Agent, depth 1: checks the exempt list. Utilities, rent, rates and taxes, insurance premiums, subscriptions under a signed contract, fees under an engagement letter. Evidence: the exempt category matched, or none.
3. Agent, depth 3: routes exempt invoices for approval by the budget holder named in the contract or supplier record. Evidence: the routing and the category.
4. Agent, depth 1: identifies the likely requester for non-exempt invoices. The contact named on the invoice, past orders from the supplier, the cost centre that usually buys from them. Evidence: how the requester was identified.
5. Agent, depth 3: asks the requester to confirm. Did you order this, was it received, and is the amount right? Evidence: the request and the answer.
6. Agent, depth 2: drafts a retrospective requisition if the requester confirms. The draft records that the order is retrospective and why. Evidence: the draft.
7. Person, procurement: approves or rejects the retrospective requisition. Evidence: the decision.
8. Person, budget holder: approves the invoice in the normal way once the requisition is approved. Evidence: the approval.
9. Agent, depth 2: reports repeat cases by requester, cost centre and supplier, for procurement. Evidence: the report.

Why not raise a purchase order automatically?

Because it would hide the failure the order was meant to catch. An order raised after the invoice arrives, simply to make the three-way match pass, makes the record look as if the purchase was approved in advance. It was not. Auditors look for exactly this pattern, and a system that produces it automatically will draw their attention to every purchase.

The agent therefore drafts a requisition that says plainly it is retrospective, and procurement approves it as such. Whether an agent may raise ordinary, forward-looking orders is a separate question, covered in can an AI agent raise a purchase order. The upstream process that should prevent most no-order invoices is in processing purchase requisitions.

What stays with a person?

Procurement decides whether a retrospective purchase is acceptable, and may decide it is not: an unapproved purchase from a supplier without a contract may need to be returned, renegotiated or escalated. The budget holder approves payment. Procurement also owns the conversation with repeat offenders, which is about behaviour, not invoices.

The exempt list stays with procurement too. If the agent could add categories, everything awkward would become exempt.

Which controls matter, and what evidence do they leave?

Order search before classification. Evidence: the search result on every no-order invoice.

Exempt list versioned. Evidence: the list version and category on each exempt routing.

Requester confirmation. The person who ordered confirms receipt. Evidence: their answer, stored with the invoice.

Retrospective marked as retrospective. Evidence: the flag on the requisition and order.

Repeat reporting. Evidence: the periodic report and procurement's response.

What should you measure?

• No-order invoices as a share of all invoices, overall and by cost centre.
• Exempt against non-exempt, to see whether the list is right.
• Time from receipt to approval for no-order invoices, compared with matched ones.
• Requesters not found, where the agent could not identify who ordered.
• Repeat requesters, and whether the number falls after procurement follows up.

Where does it usually go wrong?

The requester cannot be found. The invoice names nobody and the supplier is new. Send it to procurement rather than guessing a cost centre.

Requesters confirm without checking. "Yes, that's fine" arrives within seconds. Ask a specific question, such as the quantity received, rather than a yes or no.

Exempt categories creep. "Software" becomes exempt because subscriptions are, and then all software purchases skip ordering. Keep exemptions narrow and tied to contracts.

Matching rules are bent. Once a retrospective order exists, the invoice matches perfectly, of course. Matching works best when the order came first; see can an AI agent match invoices to purchase orders.

Where Pryme fits

In Pryme, raising a purchase order and drafting a retrospective requisition are separate capabilities. The agent on this process holds only the second, so it cannot make a no-order invoice look approved in advance. Each draft is filed with the requester's confirmation attached.