Invoice Fraud: Types, Red Flags, and How to Prevent It

Invoice fraud is one of the easiest ways for money to leave a business without anyone noticing right away. A fake invoice, a quietly changed bank account, or the same bill paid twice can slip through an accounts payable team that is busy and trusts what lands in the inbox. The dollars add up fast: business email compromise alone, much of it invoice redirection, drives billions in reported losses every year. This guide explains what invoice fraud is, the common types and red flags, how to detect and prevent it, who is liable, and what to do if you suspect it.

What is invoice fraud?

Invoice fraud is any scheme that uses a fake, altered, or duplicate invoice to trick a business into paying money it does not owe or sending a legitimate payment to the wrong account. It can come from an outside scammer impersonating a vendor, a real vendor overbilling, or an employee inside the company. The common thread is a payment that looks routine but is not.

Most invoice fraud works precisely because invoices are routine. Accounts payable processes hundreds or thousands of them, and a single fraudulent one only has to look normal enough to clear approval. That is why the defense is rarely about catching an obvious fake and usually about having checks that every invoice, including the real ones, has to pass.

What are the most common types of invoice fraud?

The most common types of invoice fraud are fake vendor invoices, business email compromise with bank-detail redirection, duplicate invoice submissions, ghost (shell) vendors, and inflated or padded invoices. Some are run by outside criminals impersonating suppliers, and some are internal schemes where an employee creates or approves bills for their own benefit.

The schemes AP teams encounter most often:

Fake vendor invoices: a bill from a vendor you never ordered from, often for plausible services like consulting, office supplies, or software, hoping it gets paid without scrutiny.
Business email compromise (BEC): a scammer poses as a known vendor or executive and emails new bank details, redirecting a real payment to their account.
Duplicate submission: the same invoice is submitted twice, sometimes with a tiny change to the invoice number, so it gets paid more than once.
Ghost vendors: an employee sets up a shell company in the vendor master file and approves invoices to it for goods or services that were never delivered.
Inflated or padded invoices: a real vendor or insider bills for more units, higher rates, or extra line items than were actually agreed or delivered.

What are the red flags of invoice fraud?

The biggest red flags of invoice fraud are an unexpected change to a vendor's bank details, urgency or pressure to pay quickly, round or unusually high amounts, an invoice with no matching purchase order, duplicate or out-of-sequence invoice numbers, and small formatting or contact-detail changes from a vendor's normal invoices. Any one of these is a reason to slow down and verify.

Watch for these warning signs in particular:

New payment instructions: a request to update a vendor's bank account, especially by email and especially marked urgent.
Manufactured urgency: pressure to pay today to avoid a late fee, a service cutoff, or an executive's displeasure.
Just under the threshold: an amount that lands just below the level that would require a second approver.
No PO or no receipt: a charge that cannot be tied back to a purchase order or proof the goods or services arrived.
Round numbers: even, rounded totals where you would expect odd cents from real quantities and tax.
Subtle mismatches: a logo, email domain, address, or invoice format that is slightly off from the vendor's usual bills.

How do you detect invoice fraud?

You detect invoice fraud by checking every invoice against independent records before paying: match it to a purchase order and a goods receipt, confirm the vendor exists in your approved master file, screen for duplicates by invoice number and amount, and verify any change to bank details through a known phone number rather than the contact on the invoice. Consistent checks catch what a quick glance misses.

Detection works best as layered controls rather than one big review. Three-way matching catches inflated quantities and prices by comparing the invoice to the order and the receipt. A clean vendor master file with no duplicate or dormant records makes ghost vendors and altered details stand out. A duplicate check on the invoice number, vendor, and amount stops the same bill being paid twice. For deeper coverage, structured three-way matching in accounts payable and a deliberate duplicate invoice detection step are the two checks that catch the largest share of fraudulent and erroneous payments.

How can you prevent invoice fraud?

You prevent invoice fraud by separating duties so no single person can both create a vendor and approve its payment, verifying bank-detail changes out of band, requiring purchase orders for spend above a set level, keeping the vendor master file clean, and standardizing how invoices are captured and reviewed. Prevention is about removing the gaps a scheme needs, not spotting every fake.

The controls that prevent the most invoice fraud:

Segregation of duties: the person who adds a vendor, the person who approves the invoice, and the person who releases payment should be different people.
Out-of-band verification: confirm any new or changed bank account by calling a number you already have on file, never the one on the new invoice or email.
PO and approval policy: require a purchase order and a second approver above a dollar threshold, and do not let invoices skip the match.
Vendor master hygiene: review the vendor file regularly for duplicates, near-duplicate names, and dormant accounts that could hide a ghost vendor.
Clean, consistent capture: get accurate invoice data into your system the same way every time so anomalies are easy to compare and spot.

These controls are part of a broader framework. A documented set of accounts payable internal controls ties them together, and teams that want the full detect-route-approve-pay cycle with built-in fraud screening often move to a dedicated accounts payable automation platform that enforces the checks automatically.

Who is liable for invoice fraud?

Liability for invoice fraud usually falls on the business that made the payment, not the bank, because the payment was authorized even though it was based on deception. Recovery from the fraudster is often difficult once funds move, and insurance coverage depends on the policy and whether reasonable controls were in place. This is why prevention matters more than chasing money after the fact.

The hard reality is that once a payment is sent to a fraudulent account, especially in a BEC scheme, the money frequently moves again within hours and becomes very hard to claw back. Banks generally are not obligated to refund a transfer the company itself authorized. Some businesses carry crime or social-engineering fraud coverage, but insurers look closely at whether the company followed its own verification procedures. Weak controls can reduce or void a claim, which makes documented controls both a prevention tool and a financial safeguard.

What should you do if you suspect invoice fraud?

If you suspect invoice fraud, stop the payment immediately if it has not cleared, then contact your bank to try to recall funds that have already been sent. Notify your finance or compliance leadership, alert the real vendor if their identity was spoofed, preserve all emails and documents as evidence, and report it to law enforcement. Speed in the first hours matters most for any chance of recovery.

Move in this order:

Halt the payment: if it is still pending, stop it; if it has gone out, call the bank at once to request a recall or freeze.
Escalate internally: tell your AP manager, controller, and compliance team so they can assess scope and other at-risk payments.
Verify with the vendor: using known contact details, confirm whether the real vendor sent the invoice or change request.
Preserve evidence: keep the invoice, emails, headers, and any payment records intact for investigation and any claim.
Report it: file with law enforcement and, in the United States, the FBI Internet Crime Complaint Center (IC3) for BEC and wire fraud.

How do you report invoice fraud?

In the United States, you report invoice fraud to your bank first to attempt recovery, then to law enforcement and the FBI Internet Crime Complaint Center (IC3) at ic3.gov for business email compromise and wire fraud. Report it internally to finance and compliance, and notify the impersonated vendor. For widespread scam invoices, you can also file with the Federal Trade Commission.

Reporting quickly does two things. It gives banks and law enforcement the best chance, however slim, of intercepting funds before they disperse, and it creates the documented record your business needs for any insurance claim and for tightening the control that failed. Treat every reported incident as a chance to find and close the gap so the same scheme cannot work twice.

Clean invoice data is the foundation of fraud detection

Most fraud checks depend on being able to compare an invoice against your records, and you cannot compare data you never captured. That is the gap InvoiceXLSX closes. Upload a PDF or image invoice and get clean Excel or CSV with the vendor, invoice number, dates, totals, and every line item in its own column, so duplicate checks, three-way matching, and amount-versus-PO comparisons run against accurate structured data instead of a stack of PDFs. From there you can extract invoice data to Excel, pull full invoice line item data to catch padded quantities and prices, and run a backlog through AI invoice data extraction so anomalies are easy to spot. When a vendor's bank details change, having the matching payment side in a spreadsheet helps too: a bank statement converter turns statements into Excel so you can reconcile what was actually paid against what was approved.