An invoice lands in your queue: no PO, no budget code, no prior approval. Someone, somewhere in the company, seemingly, made a handshake deal. The supplier delivered. And now it’s your problem. That’s shadow spend in AP. And unlike the version that shows up in expense claims, this one arrives already spent, already owed – and already awkward.
It’s not a small or occasional inconvenience. In fact, it’s likely one of your most consistent sources of stress, rework, and reputational risk. And the situation is catalysed long before the invoice ever reaches you.
Here’s the thing, though. It doesn’t have to be like this.
What shadow invoices actually cost you
Manual work:
The first, obvious cost of shadow spend to you. When an invoice arrives without a matching PO, you can’t just process it and move on.
You need to find out who ordered it, whether it was authorised, whether the amount is correct, and where it should land in the general ledger. That means emails, calls, sidling up to peoples’ desks to ask for more details and hasing approvers who’ve gone quiet.
These are days (sometimes weeks!) spent chasing facts that should have been established before the purchase was ever made.
Operational risk:
At month-end, when the books need to close accurately and on time, each unmatched invoice is a potential misstatement. A slow-burning fuse. These delays carry real operational risk – each one increases the chance that your close is wrong, late, or both.
When you’re already managing vendor invoices, employee expenses, and customer billing cycles simultaneously, the last thing you need is a pile of unmatched invoices clogging the queue right when you need to be moving fast. This is where a proper AP automation software solution earns its keep.
Audit risk:
Retroactive approval looks thin on paper. An auditor wants to see that spend was sanctioned before it was committed – not scrambled together after the invoice arrived. It’s not necessarily catastrophic. But it’s the kind of thing you end up explaining about purchases you had no part in authorising. And that explanation, however reasonable the underlying spend was, puts you in a position you shouldn’t be in.
Compliance:
Most companies have a PO policy. It exists precisely to ensure financial commitments are captured before they become liabilities. But policies only work if they’re enforced at the point of purchase. In practice, enforcement tends to be patchy. There’s no malice in it usually. It’s just that people learn that invoices get processed eventually, regardless.
So the path of least resistance is to agree the purchase informally and let AP sort it out later. Nature abhors a vacuum. In the absence of a process, people will invent their own.
Fraud and error:
The simplest risk of all – paying something you shouldn’t. The non-PO invoice process is where duplicate invoices slip through. Amounts go unchallenged. Suppliers you’ve never heard of appear in the queue with no context. You’re the last line of defence for a problem that started three departments upstream.
The problem is upstream from you
In mid-sized businesses, the AP team will be lean (perhaps you’re even a team of one). Whichever way, you process a lot payments, manage supplier relationships, and keep the whole machine ticking. You’re also the final gatekeeper, which means that when unbudgeted invoices stack up, the pressure is squarely on your shoulders.
You end up chasing other departments for information they should have captured at the point of purchase. You become the bottleneck. Not because you’re slow, but because the process upstream of you has broken down. And when a supplier chases payment on an invoice stuck in limbo, it’s your name on the reply.
That dynamic is particularly splintery when senior stakeholders are involved. When the invoice has been implicitly sanctioned by a department head or director, there’s pressure to process it quickly. Proper procedure be damned. Pushing back can feel – or genuinely be – politically uncomfortable. Even when you’re entirely right to do so.
The person who committed the spend sees no problem: from their perspective, the invoice’ll get paid eventually. The cost of that nonchalance (or indelicacy) is yours to deal with.
Ultimately, if you don’t know what’s been committed until the invoice arrives, your accruals’ll be guesswork. When your FC or CFO asks for a clear picture of outstanding liabilities, you can’t give them one with any real confidence – and that’s a visibility problem that reflects on you, not the department that bypassed the process initially.
The tech gap making shadow spend worse
Too many AP teams work with tools that weren’t built for the shadow spend problem. Spreadsheets, shared inboxes, and manual invoice matching processes can handle a clean invoice with a PO behind it reasonably well. They fall apart almost immediately when the invoice arrives without one.
Without a system that enforces a workflow before spend is committed, you’re always reactive. No visibility until the invoice lands. No record of who authorised it or when. And by then your options are limited: process it and risk approving something that was never properly sanctioned, or hold it and sour a supplier relationship you’ve spent time building.
This is the gap that AP automation software is designed to close. Not by replacing judgement, but by making sure the information exists before you need it.
The cost of manual AP processing at a glance*
| Manual process | With Webexpenses | |
| Processing time | 3,000 hrs/yr | 250 hrs/yr |
| Annual cost | £53,472 | £2,778 |
| Gross saving | £50,694/yr | |
| ROI | 34% | |
| Payback period | Under 4 months |
*Based on a mid-sized business with 250 claimants, 2 expenses per person per month, and an average salary of £35,000. Your numbers will vary.
AP automation software: What good looks like
When procure-to-pay automation and invoice processing work together properly, you’ll notice the change immediately.
Every invoice that arrives matches automatically to an approved PO. Discrepancies – wrong amounts, wrong suppliers, quantities that don’t line up – get flagged long before payment is due. Approvals happen digitally, with a clear record of who authorised what and when. Departments have a clear, simple route to raise a PO before spend is committed.
And because the whole process lives in one place, you can see exactly what’s committed, what’s pending, and what’s been paid – in real time. Not at month-end panic o’clock.
The numbers bear this out. For a mid-sized business with 250 claimants, switching from manual processing to AP automation software delivers a gross annual saving of over £50,000 – with payback in under four months.
In the end, this means your accruals are based on actual committed spend. When your FC asks for a clear picture of outstanding liabilities mid-month, you can give ‘em one. Or if an auditor asks to see the paper trail for a payment, it’s there and timestamped.
The manual chasing evaporates. Month-end inbox archaeology is gone, too.
How Webexpenses can help
Our procure-to-pay system system doesn’t do anything revolutionary. It simply makes the spend process work as intended.
Departments raise POs through the platform before spend is committed. Approvals happen digitally, with a clear record attached. When the invoice arrives, it matches automatically — and if something doesn’t line up, it gets flagged before it becomes your problem.
The manual chasing stops because the information exists before you need it. Month-end isn’t a scramble because the picture is already clear. And when your FC asks for outstanding liabilities mid-month, you’ve got an answer ready.
OCR captures and codes invoices without manual data entry. ERP integration means what hits the general ledger is right the first time. And it connects with the systems you’re already using – the usual suspects: Xero, Sage, NetSuite, Microsoft Business Central – without disrupting anything downstream that’s already working.
It’s simply adding the control and visibility you should already have. The basics, done well. Finally.
Ready to take back control of your queue? Book a demo with Webexpenses.
