It starts small. A personal dinner claimed as a client meeting. A hotel night stretched by one day. An Uber receipt submitted twice. Before long, what began as a minor fudge becomes a habit ,and habits, unchecked, become schemes.
Expense report fraud is one of the most pervasive and persistently underestimated forms of occupational fraud in the world. According to the ACFE’s 2024 Report to the Nations, expense reimbursement schemes appeared in 13% of all fraud cases analyzed ,and the average loss per case reached $251,000, with schemes running undetected for an average of 18 months before discovery. That figure has risen steadily, up $10,000 from the previous report cycle.
What makes expense report fraud so enduring isn’t complexity ,it’s the combination of low perceived risk, easy rationalization, and controls that simply haven’t kept pace with how employees now submit, manipulate, and fabricate expense documentation.
In 2025, that gap grew significantly wider.
Why Expense Report Fraud Is So Hard to Catch
Most companies trust employees to self-report business expenses. That trust, unsupported by robust controls, is the foundation on which expense report fraud is built.
According to the ACFE’s 2024 data, the most common contributor to occupational fraud ,including expense schemes ,was a lack of internal controls, cited in 32% of cases. Override of existing controls accounted for another 19%, and lack of management review for 18%. In other words, the problem is rarely that employees are unusually devious. It’s that organizations make fraud easy to commit and hard to detect.
The psychology is also well-documented. Employees rationalize expense report fraud with familiar justifications: The company owes me this. I haven’t had a raise in years. It’s just a few dollars. Nobody checks anyway. When that last belief turns out to be accurate ,and in organizations that spot-check only a fraction of submitted expenses, it often is ,the behavior escalates.
A single successful false claim becomes a pattern. And patterns compound. The 7 signs of corporate fraud most companies ignore often begin with exactly this kind of low-level, normalized misconduct that eventually grows into serious financial loss.
The 4 Main Types of Expense Report Fraud
The ACFE classifies expense report fraud into four distinct schemes. Understanding each is the first step to detecting them.
1. Mischaracterized Expenses
This is the most common form: submitting a legitimate receipt for a personal expense and classifying it as a business cost. Classic examples include a personal vacation partially billed as a business trip, a dinner with friends described as client entertainment, or home office supplies mixed in with genuine work purchases.
Mischaracterized expense claims are difficult to challenge because the underlying receipt is real. The fraud lies not in the document but in the characterization ,and without a culture of scrutiny and clear policy enforcement, these claims sail through approval.
2. Overstated or Inflated Expenses
Here, the expense itself is legitimate but the claimed amount is not. An employee spent $42 on a client lunch but submits a claim for $85. A mileage log reports 180 miles when the actual drive was 90. A hotel stay is rounded up by a night.
Inflation is often incremental ,small enough in any individual claim to appear within normal variance. But across months and multiple employees, the cumulative effect is substantial. This is one reason year-over-year expense trend analysis is so valuable as a detection tool.
3. Fictitious Expenses
The most deliberate form of expense report fraud: claiming reimbursement for expenses that never happened, supported by fabricated or doctored receipts. Until recently, this required meaningful effort ,photo editing skills, access to blank receipt templates, or purchased forgery services online.
That barrier has effectively disappeared. We cover the AI dimension in detail below.
4. Duplicate Reimbursements
Submitting the same receipt twice ,whether to two separate expense reports, across two separate periods, or through both a corporate card claim and a manual submission. According to the ACFE, duplicate reimbursements account for 21% of expense report fraud cases in small businesses and 11% in larger organizations.
Duplicates are often dismissed as innocent errors, and sometimes they are. But when the same employee submits duplicate claims repeatedly ,particularly for higher-value items ,the pattern warrants investigation. Our guide on what evidence fraud investigators actually look for explains how investigators distinguish errors from intent.
The New Threat: AI-Generated Fake Receipts
Expense report fraud has always existed. What changed in 2025 is the sophistication of the tools available to commit it.
When OpenAI launched GPT-4o’s enhanced image generation capabilities in early 2025, expense management platforms almost immediately began flagging a new wave of fraudulent submissions. According to AppZen, AI-generated receipts accounted for roughly 14% of all fraudulent documents submitted in September 2025 ,compared to essentially zero the previous year. Ramp’s detection software flagged more than $1 million in fraudulent invoices within just 90 days of deployment.
These are not crude forgeries. Modern AI-generated receipts include realistic wear and tear ,crumples, faded text, simulated thermal paper texture ,along with accurate logos, correct tax calculations, and legitimate-looking merchant names and timestamps. SAP research conducted in July 2025 found that nearly 70% of CFOs believed employees were using AI to falsify travel expenses or receipts, with approximately 10% certain it had already occurred in their organizations.
Mason Wilder, research director at the ACFE, put the stakes plainly: the barrier to entry for creating convincing fake receipts is now essentially zero. Any employee with internet access and five minutes can generate documentation that passes a manual review.
For a broader view of how AI is reshaping financial crime across the board, see our analysis of how AI-powered fraud is reshaping corporate security in 2026.
Who Commits Expense Report Fraud ,and Why It Escalates
Expense report fraud is not the exclusive domain of bad actors. Research consistently shows it cuts across seniority levels, tenure, and departments. ACFE data indicates that 20% of small businesses and 12% of larger companies experience expense fraud ,and senior employees, with higher travel budgets and less scrutiny on their claims, are frequently among those who abuse the system most.
The escalation pattern is well understood: an employee tests a small false claim. It gets approved without question. They submit another. The habit forms before the behavior ever rises to what the employee themselves would label as “fraud.” By the time an investigation begins, the scheme may have been running quietly for a year or more.
This is why expense report fraud so often surfaces alongside other misconduct. Organizations that uncover one form of employee theft frequently find others nearby. If you’ve already identified financial patterns, our guide on how to prove embezzlement without direct evidence is a practical next step.
7 Red Flags That Signal Expense Report Fraud
Finance teams and internal auditors should treat the following as triggers for closer review:
- Round-number claims without itemized receipts ,particularly for meals, travel, or entertainment
- Expenses submitted on weekends or holidays when business activity would be unusual
- Duplicate vendor names or receipt amounts appearing across different reporting periods
- Receipts from the same merchant on consecutive days for the same employee
- Mileage claims that don’t align with calendar or meeting records
- Expenses submitted immediately before a resignation or termination ,a common pattern as employees extract final value before leaving
- Receipt images that appear unusually perfect ,no shadows, uniform fonts, no handwriting ,which may indicate AI generation
The last red flag deserves special attention given the 2025 surge in AI-generated documentation. As one SAP Concur executive warned clients directly: Do not trust your eyes when reviewing submitted receipts. Detection now requires technical verification ,metadata analysis, hash comparison, and image forensics ,not just a visual check.
How to Prevent and Detect Expense Report Fraud
The good news is that expense report fraud is among the most controllable forms of occupational fraud, because it relies entirely on a weak or absent review process. Organizations that address this directly see significant reductions in fraudulent submissions.
Start with a clear, enforced policy. An expense policy that specifies reimbursable categories, per-item spending limits, required documentation, and approval chains removes the ambiguity that fraudsters exploit. Policies should be reviewed at least annually and communicated to all employees ,not buried in an onboarding document nobody rereads.
Require original, itemized receipts. Requiring detailed receipts ,not just credit card statements ,for all claims above a defined threshold is one of the AICPA’s core recommendations for preventing expense report fraud. Itemization allows reviewers to verify that claimed expenses match the merchant’s actual offerings.
Implement mandatory supervisory approval. Every expense report should be reviewed and approved by someone who is not the submitter ,ideally someone familiar with the employee’s actual schedule and travel activity. Approval by executive-level employees should require board-level sign-off.
Audit systematically, not just randomly. Organizations that only spot-check create an 80% chance of non-detection that employees quickly calculate. Automated expense management platforms that apply policy rules at 100% coverage close this gap entirely. Comparing reported expenses against calendar data, meeting records, and corporate card statements surfaces inconsistencies that manual review misses.
Use technology to fight technology. Given the 2025 surge in AI-generated fake receipts, organizations must deploy detection tools capable of metadata analysis, digital fingerprinting, and image consistency checks. The ICAEW notes that AI detection tools can now identify hidden digital signatures left by image generation software ,artifacts that are invisible to human reviewers but detectable by machine learning models.
For organizations managing the aftermath of discovered fraud, our guides on what to do before confronting a suspected employee and how to recover money from an embezzling employee cover the critical next steps.
Small Claims, Large Consequences
The deceptively modest scale of individual expense report fraud claims is precisely what makes them dangerous. A $200 false claim, repeated monthly across a department, becomes a six-figure annual loss before any single transaction raises a flag. Multiply that across years and multiple employees, and the cumulative exposure is enormous ,as the ACFE’s average loss figure of $251,000 per scheme confirms.
The combination of weak controls, easy rationalization, and now AI-powered fabrication tools means expense report fraud is not declining ,it’s evolving. Organizations that treat it as a minor administrative nuisance are bearing costs they’ve simply never measured.
The solution is not distrust. It’s infrastructure: clear policies, systematic review, modern detection tools, and a culture where integrity is enforced, not assumed. FraudOrder provides the resources to build that infrastructure at every stage ,from prevention and detection through investigation and recovery.
Frequently Asked Questions (FAQ)
Q1: How common is expense report fraud in small businesses?
According to the ACFE’s 2024 data, 20% of small businesses with fewer than 100 employees experience expense report fraud ,a higher rate than larger organizations, primarily because small businesses tend to have fewer formal controls and less oversight infrastructure. The median loss is also disproportionately damaging relative to revenue. Our guide on small business embezzlement vulnerabilities explores why smaller organizations are particularly exposed.
Q2: Can an employee be fired and prosecuted for expense report fraud?
Yes on both counts. Expense report fraud constitutes theft and can support both termination for cause and criminal charges, depending on the amount involved, the jurisdiction, and whether law enforcement chooses to prosecute. Civil recovery is also an option. For context on termination decisions, see our guide on whether you can fire someone for embezzlement without going to the police.
Q3: What’s the difference between expense fraud and an honest mistake?
The key distinction is intent. Accidentally submitting the same receipt twice due to disorganization is an error; deliberately doing so for financial gain is fraud. Investigators look for patterns ,repeated mischaracterizations, escalating claim amounts, and claims that consistently exploit policy gaps ,to distinguish honest mistakes from deliberate misconduct. A single anomaly warrants a conversation; a pattern warrants an investigation.
Q4: How are AI-generated fake receipts detected?
Manual review is no longer sufficient. Detection now requires metadata analysis ,checking when and how an image file was created ,along with digital fingerprinting to identify AI generation artifacts, hash comparison to catch duplicate image files submitted under different names, and merchant validation to confirm the vendor’s actual pricing matches what was claimed. Organizations should deploy purpose-built expense management platforms with these capabilities built in, rather than relying on human reviewers alone.
Q5: How long does expense report fraud typically go undetected?
The ACFE’s 2024 report puts the average detection time for expense reimbursement schemes at 18 months. Schemes involving senior employees or weak supervisory review often run longer. The longer the scheme runs, the greater the total loss ,and the more complex the investigation becomes. Early detection through systematic auditing and automated controls is significantly more cost-effective than reactive investigation after the fact.
Q6: What should I do if I suspect a colleague is committing expense report fraud?
Document your observations ,dates, amounts, patterns, and any supporting evidence ,without confronting the individual directly. Report your concerns through your organization’s whistleblower or ethics hotline; the ACFE finds that 43% of occupational frauds are initially detected through tips, with employees as the most common source. If your organization lacks a formal reporting channel, escalate to your compliance officer, internal audit team, or legal counsel. For guidance on what investigators need to build a case, see our article on what evidence fraud investigators actually look for.