Managing employee absence is challenging enough without having to question someone’s honesty. But what happens when a long-term sick note starts to raise suspicions? Across multiple industries, employers are dealing with a growing issue: staff members who claim to be unfit for work, while secretly working elsewhere.
This behaviour, which is often referred to as “moonlighting”, isn’t just a breach of trust. In many cases, it’s a direct breach of contract, a violation of sick pay policy, and potentially grounds for dismissal or legal action.
At B25 Private Investigation, we support employers across the UK who are facing these difficult situations. Here’s how our team investigates cases of suspected sick leave abuse, what employers need to know, and how we helped one construction company uncover the truth behind a suspicious sickness absence.
What Is Employee Moonlighting?
Moonlighting refers to an individual working a second job — or running their own business — without the knowledge or consent of their primary employer. When this happens during periods of authorised sick leave, it becomes a serious concern.
The problem isn’t limited to one sector. We’ve seen cases involving:
- Construction workers claiming to be injured, while working on private jobs
- Nurses or healthcare assistants off sick from the NHS, but still doing agency shifts
- Drivers suspended for medical reasons, who are found working for delivery firms
- Office staff working freelance under a different name while on long-term stress leave
Whether the motivation is financial pressure or opportunism, the result is the same, the employer is misled, and potentially paying sick leave to someone actively working elsewhere.
Why It Matters for Employers
Aside from the obvious fairness issue, moonlighting during sick leave can have serious consequences for a business:
- Financial loss through continued salary or statutory sick pay
- Increased pressure on colleagues covering the absence
- Damage to morale if the deception becomes known
- Legal implications around benefits fraud or breach of contract
- Risk to reputation if clients or the public become aware
It also puts employers in a difficult position. While it’s important to respect medical leave, there are moments when suspicion is justified, and that’s where professional investigation can help.
A Real Life Case Study: The Self-Employed Bricklayer
Please note: This example shows a similar situation to a recent case undertaken by B25 Private Investigation. All client cases handled by B25 remain strictly confidential and names and details have been changed.
Our client, a medium-sized construction firm in the South West, had a skilled bricklayer who had been off for six weeks with a reported back injury. While the company was sympathetic, a colleague mentioned seeing the same employee working on a nearby private project.
The employer had no desire to jump to conclusions, but they needed to protect their business. They contacted B25 for a confidential consultation.
We began with discreet background research and identified that the employee had recently registered a sole trader business in their own name. Our investigators then carried out targeted surveillance over several days.
The subject was observed driving to a residential renovation site and carrying out physically demanding brickwork, including lifting, bending, and climbing ladders with no visible sign of restriction. We gathered time-stamped video footage and stills that clearly contradicted the claimed injury.
This evidence allowed the employer to begin formal disciplinary proceedings. It also supported their decision to report the matter to HMRC and withdraw sick pay entitlements. Because the investigation was carried out lawfully, proportionately, and with full documentation, it stood up to legal scrutiny.
The outcome was a clean resolution, with minimal disruption to the rest of the team.
How B25 Investigates Suspected Sick Leave Fraud
We take a methodical and ethical approach to every case. Our goal is to establish facts, not to entrap or accuse. Our services include:
- Covert surveillance, including video and photographic evidence
- Background checks, including business registrations, social media activity, and online presence
- Vehicle tracking, where appropriate and legally compliant
- Witness statements, where other employees or third parties are involved
- Detailed reports, formatted for HR, legal teams, or employment tribunals
All our investigators have extensive experience in military, police, or intelligence backgrounds. We work with absolute discretion and full compliance with UK law, including data protection and privacy regulations.
Is It Legal to Investigate an Employee?
Yes, as long as the investigation is proportionate, justified, and handled by a qualified professional. UK employment law allows for investigation where there are reasonable grounds to believe an employee may be acting dishonestly or violating their contractual obligations.
Employers should not attempt to carry out surveillance themselves. Doing so could breach data protection laws or lead to accusations of harassment. By working with an accredited private investigator, you ensure that all evidence is gathered legally and professionally.
When to Seek Help from a Professional
If you have a genuine concern about an employee abusing sick leave, it’s important to act early. Delaying can cost your business time, money, and morale.
You may want to consider a private investigation if:
- There’s a tip-off or credible report of the employee working elsewhere
- You’ve seen suspicious social media activity or conflicting public claims
- Their reported illness or injury doesn’t match observed behaviour
- The absence is part of a pattern, or linked to sensitive internal changes
Even if you\’re unsure, a consultation with B25 can help you assess your options without escalating unnecessarily.
Do you Need a Private Investigator In London, Bristol, Gloucester, Swindon, Exeter or Plymouth?
Employee moonlighting during sick leave is more common than many employers realise, and it’s not always easy to detect. But with the right support, it’s possible to uncover the truth, protect your business, and move forward with confidence.
At B25, we approach every case with professionalism, discretion, and a commitment to ethical practice. Whether you’re managing a small team or a large workforce, we can help you get the clarity you need.
To speak with a member of our investigations team in complete confidence, get in touch with B25 Private Investigation today. We have offices in London, Bristol, Gloucester, Swindon, Exeter, Plymouth and Weston Super Mare and are happy to take on cases wherever you are based in the UK. We have 5* Google reviews and will always work in your best interests to solve your case.