Signs of Employee Fraud in the Workplace

In my experience, employee fraud is rarely the work of a reckless opportunist. The cases we investigate most often involve someone who has been trusted — sometimes for years — and who has used that trust methodically and quietly. By the time a board or finance director calls us, the damage is usually far greater than anyone anticipated, and the window for clean recovery is narrower than it should be.

That is not a criticism. These situations are genuinely difficult to see from the inside. Familiarity distorts perception, and the people best positioned to notice the warning signs are often the ones least inclined to believe them. What I can offer here is a frank account of what those signs actually look like — drawn from the investigations we have carried out — and some guidance on when to act.

What Is Employee Fraud?

Employee fraud — sometimes called occupational fraud or internal fraud — is any deliberate deception carried out by an employee for personal financial gain at the employer’s expense. In practice, that covers a wide range of conduct: falsified expense claims, payroll manipulation, asset misappropriation, vendor fraud, invoice redirection, and the theft of commercially sensitive data.

The Association of Certified Fraud Examiners (ACFE) groups occupational fraud into three broad categories: asset misappropriation, corruption, and financial statement fraud. Asset misappropriation — skimming, billing schemes, inventory theft — is by far the most common. Financial statement fraud is rarer but tends to produce the most significant losses when it does occur.

What makes employee fraud distinct from external fraud or cybercrime is deceptively simple: the perpetrator is already inside. They have legitimate access, institutional knowledge, and — crucially — the benefit of the doubt. They do not need to breach anything. They just need to exploit what they already have.

How Common Is Employee Fraud?

More common than most organisations are comfortable admitting — and significantly underreported. The ACFE’s Report to the Nations found that a typical fraud scheme runs for twelve months before it is detected, with a median loss per case of $145,000 (approximately £115,000). Globally, occupational fraud is estimated to cost organisations around five percent of annual revenue.

In the UK, the picture is consistent with that. Internal fraud consistently features in the Fraud Advisory Panel’s annual data as a material risk for businesses of all sizes. What the statistics do not capture are the cases that never make it into any dataset — resolved quietly, managed informally, or simply never identified at all. In my experience, those represent the majority.

When I speak to clients who have just discovered a fraud, one of the most common things they say is: “We had a feeling something was off, but we couldn’t put our finger on it.” The warning signs were there. They just weren’t being read as warning signs.

15 Warning Signs of Employee Fraud

None of the indicators below is, on its own, proof of fraud. What matters is pattern and context. A single anomaly can usually be explained. A cluster of them, involving the same individual, function, or system, is something different. These are the patterns I return to again and again in our investigations.

1. Unexplained Financial Discrepancies

Variance between forecast and actual figures that cannot be reconciled through ordinary business activity is where most investigations begin. Fraudulent transactions rarely announce themselves. What we typically see are small, frequent payments sitting just below approval thresholds, recurring adjustments to supplier invoices, or unexplained credits that appear and disappear in the same cycle.

The tell is usually not the size of the discrepancy. It is the pattern. Administrative errors tend to be random and correctable. Fraud tends to be consistent and directional. If the same account, the same vendor, or the same individual appears repeatedly at the centre of unexplained variances, that warrants a closer look.

2. Missing or Altered Documentation

Legitimate transactions leave a paper trail. When documentation — purchase orders, delivery receipts, bank statements, approval records — is routinely absent, amended without explanation, or suddenly difficult to obtain from a particular person, that is not a filing problem. It is a control problem.

Something I see regularly is documents that have been printed, altered, and re-scanned to remove metadata. It is a basic technique, but it works well enough in environments where no one is looking. If you find yourself being told that a document “can’t be located” more than once in relation to the same individual or process, that should register.

3. Employees Refusing to Take Annual Leave

This is one of the most consistently underestimated indicators on this list. An employee who refuses annual leave, insists on being the only person who can manage their responsibilities during an absence, or becomes noticeably anxious when asked to hand over duties — even temporarily — may well be protecting something that requires their continuous presence to remain concealed.

Fraud schemes need maintenance. Fraudsters need to intercept queries, suppress anomalies, and respond to anything that might draw attention. That is hard to do from a beach in Tenerife. Mandatory leave rotation is one of the most effective fraud prevention controls available to any organisation, and it costs nothing to implement. The ACFE has consistently identified the absence of job rotation as an environmental risk factor for sustained fraud.

4. Lifestyle Materially Beyond Known Income

A new car, a renovation, business-class travel to destinations that don’t map to any client relationship. In isolation, any of these might mean nothing. People come into money for all sorts of legitimate reasons. But when lifestyle inflation coincides with access to company funds, elevated purchasing authority, or a procurement function with limited oversight, it becomes a data point worth examining.

I want to be clear: this indicator requires careful, proportionate handling. The instinct to jump to conclusions is understandable, but acting on it without further investigation creates its own legal risks. What it warrants is closer scrutiny — not confrontation.

5. Excessive Control Over Processes or Relationships

Fraud requires control. Not just access, but the ability to manage the environment well enough that anomalies don’t surface. An employee who actively resists supervision, deflects audit enquiries, keeps supplier or client relationships entirely to themselves, or becomes disproportionately protective of specific systems or data sets is, whether intentionally or not, creating the conditions in which fraud can persist.

This pattern is most common in finance, procurement, and payroll — functions where an individual’s authority over approvals and payments creates structural opportunity. When that authority is combined with an unwillingness to be overseen, the risk profile changes significantly.

6–15. Further Indicators Warranting Attention

The following patterns become significant when observed alongside the primary indicators above. Individually, they are inconclusive. In combination, they form a picture:

• Unusual working patterns — arriving very early or staying very late without clear operational reason, particularly when it falls outside of peak business periods.
• Unexplained close relationships with suppliers or contractors, especially where the same employee manages payment or approval processes connected to those parties.
• Colleague complaints or concerns about irregularities that have been raised informally but not formally escalated or recorded.
• Duplicate payments, overpayments, or payments to bank accounts that do not correspond to verified supplier records.
• Resistance to system upgrades or internal audit processes — particularly where the change would introduce automated reconciliation or tighter access controls.
• System access that materially exceeds what the employee’s role requires.
• Discrepancies between physical stock or asset levels and recorded inventory, especially where the same individual oversees both.
• Falsified qualifications, credentials, or employment history surfaced through pre-employment or periodic background screening.
• Undeclared conflicts of interest — relationships with suppliers, clients, or competitors that have never been formally disclosed.
• A high volume of voided or refunded transactions processed by a specific individual, without adequate business justification.

Industries Most at Risk From Internal Fraud

Employee fraud can take root in any organisation given the right conditions. In practice, certain industries recur with greater frequency in the cases we handle and in the broader research literature. Operational complexity, transaction volume, and the strength of internal controls are the key variables.

Financial services and banking: high transaction volumes, complex reconciliation requirements, and strong individual financial incentives create a concentrated combination of opportunity and motivation.

Construction and engineering: procurement fraud, inflated subcontractor invoices, and kickback arrangements are common in project-based environments with multiple supplier relationships and limited central oversight.

Healthcare and pharmaceuticals: procurement irregularities, billing fraud, and the misuse of research or operational budgets feature regularly in reported cases.

Retail and hospitality: cash-handling environments with high staff turnover and stretched supervisory capacity present structural vulnerability, particularly at branch or site level.

Professional services: expense fraud, client billing irregularities, and undisclosed conflicts of interest are the most common presentations.

Local government and public sector: procurement fraud and payroll manipulation are consistently the most frequently reported categories in publicly available data.

Private equity-backed businesses and family offices are an area I would flag specifically. Periods of rapid growth, post-acquisition integration, or management transition are when internal controls most often lag operational complexity. They are also when a person who understands the gaps can exploit them most effectively.

When Should Employers Investigate?

The instinct to manage suspected fraud informally — a quiet conversation with HR, a managed exit, a line management intervention — is something I understand. It feels contained and proportionate. In practice, it is one of the most common ways organisations make a difficult situation worse.

An unstructured internal response can destroy evidence, expose the organisation to constructive dismissal or wrongful termination claims, and in some cases create a reporting liability if the conduct involves money laundering or other notifiable offences. The quiet exit that seemed to solve the problem can reappear as a significant legal exposure twelve months later.

Professional investigation becomes necessary when:

• Financial irregularities cannot be reconciled through internal review alone.
• A specific individual is the subject of credible and substantiated concern.
• The potential financial loss or reputational exposure is material.
• The suspected conduct involves a senior employee, director, or someone with elevated system or financial access.
• There is a conflict of interest that makes a genuine internal investigation unreliable or inappropriate.
• Legal proceedings — civil recovery, disciplinary action, or criminal referral — may follow, requiring evidentially sound findings.

The timing question matters more than most people realise. Fraud schemes become harder to unpick the longer they run. Evidence gets deleted, funds are moved, and the people involved have more time to coordinate their accounts. The earlier we are brought in, the more options the client has.

How Professional Fraud Investigations Work

When a client comes to us with a concern about internal fraud, the first thing we do is listen carefully — not just to what they suspect, but to what they know, what they don’t know, and what outcome they are actually trying to achieve. Those are not always the same thing, and the investigation needs to be structured accordingly.

A typical engagement with iSpy Detectives proceeds through the following stages:

Initial scoping and risk assessment: understanding the nature of the suspected conduct, the individuals involved, the available evidence base, and what a successful outcome looks like for the client.

Covert preliminary enquiries: where appropriate, background intelligence gathering to establish whether the concern has real substance before any overt step is taken that could alert the subject.

Evidence collection and preservation: document review, financial analysis, digital forensics, and where required, surveillance — all conducted in strict compliance with GDPR, RIPA, and relevant employment law.

Witness interviews: structured, legally defensible interviews with relevant parties, conducted by experienced investigators who understand the disciplinary and litigation context.

Findings report: a clear, factual report setting out the evidence obtained, the methodology employed, and the conclusions reached — written to be used by legal advisers, insurers, or enforcement agencies if required.

Post-investigation support: practical assistance with disciplinary proceedings, asset recovery referrals, or engagement with the National Crime Agency, Action Fraud, or the Serious Fraud Office as appropriate.

Everything we do is conducted within the legal and regulatory framework applicable in England and Wales. We are not in the business of cutting corners to get a result faster. A finding that cannot withstand legal scrutiny is not a finding.

Concerned about internal fraud? Speak to our corporate investigations team.

Conclusion

Employee fraud does not arrive with a warning. It grows gradually inside the normal rhythm of business, hidden behind familiar faces and ordinary-looking transactions. The indicators in this guide are not a checklist for certainty. They are a framework for attention — the patterns that those of us who investigate fraud professionally have learned to take seriously.

What I consistently see in the organisations that handle these situations well is not that they had better luck, or even better controls. It is that when something felt wrong, they acted on it rather than rationalising it away. The concern was taken seriously, the right people were brought in early, and the response was structured and proportionate.

If something in your organisation is giving you cause for concern — whether at board level, within a specific team, or in a function you haven’t been able to see clearly — we are happy to have a confidential conversation about what that might mean and what your options are.

Frequently Asked Questions

What is the most common type of employee fraud?

Asset misappropriation accounts for around 86% of occupational fraud cases in the ACFE’s research — and in my experience that figure rings true. Billing schemes, where fraudulent invoices are submitted through fictitious or controlled vendor entities, are among the most common forms we encounter, along with expense reimbursement fraud and payroll manipulation. The cases are often unremarkable in their mechanics. What makes them significant is how long they run before anyone notices.

How do companies detect fraud?

Tip-offs remain the most common detection route, accounting for over 40% of discovered cases in ACFE data — and the majority of those come from employees, not external parties. That tells you something important about the value of an environment where people feel genuinely safe raising concerns. Beyond tip-offs, internal audit, management review, and accidental discovery are the next most frequent routes. In our experience, professional investigation is typically engaged once a concern has been identified internally but the organisation lacks either the capacity or the independence to investigate it properly.

Is employee fraud a criminal offence?

Yes. Depending on the nature of the conduct, employee fraud in England and Wales may constitute an offence under the Fraud Act 2006, the Theft Act 1968, the Computer Misuse Act 1990, or the Bribery Act 2010. Criminal referral can be made to the police, the Serious Fraud Office, or — where public funds are involved — other relevant agencies. Civil recovery is also available and can run alongside or independently of any criminal process. My strong advice is to take legal counsel at the earliest stage, so that the approach to investigation does not inadvertently prejudice either route.

Our Related Services

If you would like to understand more about the specific investigation services we provide, the following pages may be relevant:

• Corporate Fraud Investigations
• Internal Fraud Investigations
• Workplace Investigations