If your AP team has ever caught a vendor bank-detail change that turned out to be a scammer’s account after the wire already went out, you already know the approval process wasn’t the weak point. The weak point was that nobody called back on a verified number before releasing the payment. That single missed step is behind most of the accounts payable fraud losses that actually make it through.

What Is Accounts Payable Fraud?

Accounts payable fraud is the deliberate exploitation of a company’s invoice and payment cycle to divert funds, whether by an outside actor, an employee, or both acting together.

Put simply: it is any scheme that gets a payment approved and released to somewhere it should not go.

As Ramp defines it: “The deliberate exploitation of your company’s payment process for unauthorized financial gain.” (Ramp, 2026)

This overlaps with but is not identical to document forgery (planned entry): forgery is one method AP fraud uses, not the whole category. Common schemes:

• Ghost vendors: fake suppliers created to submit invoices for goods or services never rendered
• Business email compromise: a vendor’s email is spoofed or hacked to redirect payments to a fraudulent account
• Duplicate or altered invoicing: the same invoice submitted twice, or a real invoice’s amount or payee changed

How Accounts Payable Fraud Is Detected and Prevented

Three-way matching is the control named most often across every major AP fraud guide, KlearStack’s competitors included.

Control	What it does	Stops
Segregation of duties	No single employee can create a vendor, approve an invoice, and release payment	Kickbacks, one-person schemes
Three-way matching	PO, receiving document, and invoice checked against each other before payment	Ghost vendors, overbilling
Callback verification	Bank-detail changes confirmed by phone on a pre-saved number, never by email	Business email compromise
Anomaly detection	Vendor behavior and invoice metadata checked against historical baselines	Invoice splitting, timing attacks

Accounts Payable Fraud vs. Invoice Fraud

These get used interchangeably, but AP fraud is the broader category. Invoice fraud is specifically about a fraudulent document. AP fraud also covers schemes with no forged document at all, like a kickback or an insider-created ghost vendor.

Term	Scope	Example
AP fraud	Any exploitation of the payment process	An employee approves invoices from a vendor they secretly own
Invoice fraud	Specifically a fraudulent invoice document	A scammer submits a fake invoice for goods never delivered

Every invoice fraud is a form of AP fraud. Not every AP fraud involves a fraudulent invoice, which is why purchase order matching alone doesn’t close every gap.

Why Accounts Payable Fraud Matters for Finance Teams

For a CFO or AP manager, accounts payable fraud is a direct hit to four buyer metrics, not an abstract compliance risk.

• Cost-per-document: every fraud investigation adds manual review hours no automated workflow accounts for
• Error and exception rate: fraud schemes are specifically designed to look like normal exceptions
• Cycle time: callback verification and manual anomaly review both slow down legitimate payments if they aren’t automated
• It’s also the core risk KlearStack’s accounts payable automation is built to reduce, not just process faster

See how KlearStack flags a fraudulent vendor change before the payment goes out.

Accounts Payable Fraud Benchmarks

The scale here isn’t hypothetical. 76% of US organizations experienced attempted or actual payments fraud in 2025, and 74% were hit by business email compromise specifically. (AFP, 2026)

• Average loss to occupational fraud: 5% of annual revenue, median $145,000 per case (ACFE, 2024)
• Organizations using AI for fraud mitigation: only 17% (AFP, 2026)

Reconciliation controls like SAP reconciliation catch what manual review misses, but only if the data feeding them is accurate in the first place.

The median AP fraud case costs $145,000. Talk to us about the controls that catch it earlier.

Common Mistakes and Limitations

AP fraud controls fail in a few predictable ways.

• Email-only vendor verification: a bank-detail change gets approved based on an email that looks legitimate, with no callback to confirm it
• No segregation of duties: the same person who creates a vendor can also approve and release payment to them
• Static approval thresholds: invoices submitted just under the manual-review limit go straight through, a gap fraudsters specifically test for
• Verification without automated document verification backing it: a reviewer approves a document that looks right but was never actually checked against source records

Real-World Example

Worked hypothetical, not an audited case study. An AP team receives an email that appears to be from a long-standing vendor, requesting an updated bank account for future payments.

• The request routes to a reviewer instead of an auto-update, per human-in-the-loop (planned entry) policy
• A callback to the vendor’s verified phone number, not the one in the email, confirms the request is fraudulent
• The payment that would have gone to the fraudulent account is redirected to the real vendor instead

If your AP team still verifies bank-detail changes by email alone, you already know how this ends. Let’s fix that.

Conclusion

Accounts payable fraud rarely announces itself. It looks like a normal vendor email, a normal invoice, a normal request to update banking details, right up until the payment lands somewhere it shouldn’t. The controls that actually stop it, three-way matching, callback verification, segregation of duties, aren’t sophisticated. They are just consistently skipped under volume and time pressure.

For KlearStack’s buying committee, the real cost of AP fraud is not the fraud itself. It is the manual, inconsistent way most teams try to catch it, one email and one phone call at a time. The question worth asking is not whether your AP team knows the warning signs. It is whether every invoice gets checked against them, every time, regardless of who is busy that week.

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