How to Investigate Employee Absenteeism Lawfully

Employee absenteeism can place considerable pressure on a business. Unplanned absences may disrupt operations, increase workloads for colleagues and make it harder to maintain consistent customer service.

Most sickness absence is genuine. Employees may need time away from work because of physical illness, mental ill health, disability, injury or difficult personal circumstances. These situations should be handled fairly and sensitively.

However, employers may occasionally identify evidence suggesting that an employee is misrepresenting their condition, working elsewhere while claiming sick leave or carrying out activities that appear inconsistent with stated medical restrictions.

Investigating employee absenteeism requires a balanced approach. Employers need to protect the organisation while respecting privacy, employment rights, disability protections and data-protection law.

This guide explains how to identify absence concerns, what internal steps should be taken and when an independent investigation may be appropriate.

 

What Is Employee Absenteeism?

Employee absenteeism generally means repeated or prolonged absence from work. It may include authorised sickness absence, unauthorised absence or recurring short-term absence.

Absenteeism is not automatically misconduct. A pattern of absence may be caused by:

• A physical or mental health condition
• A disability
• Work-related stress
• Pregnancy-related illness
• Family or caring responsibilities
• Bereavement
• Problems within the workplace
• A genuine long-term injury

The CIPD’s 2025 Health and Wellbeing at Work report found that UK employees were absent for an average of 9.4 days per year. Mental ill health was the leading cause of long-term absence, while stress contributed significantly to both short and long-term sickness absence.

This makes it important for employers to begin with support, clear communication and a fair absence-management process rather than assuming dishonesty.

 

How Employee Absenteeism Affects a Business

Even where an absence is genuine, frequent or prolonged absence can have a significant operational effect.

 

Lost Productivity

Work may be delayed, reassigned or left incomplete. Managers may need to reorganise rotas, postpone projects or recruit temporary cover.

 

Higher Employment Costs

The organisation may need to meet sick-pay obligations while also paying overtime, agency fees or additional recruitment costs.

 

Pressure on Colleagues

Repeated staff shortages can force other employees to take on additional responsibilities. Over time, this may contribute to stress, burnout and reduced morale.

 

Customer and Service Disruption

Absence in a specialist or customer-facing role may affect response times, service standards and important commercial relationships.

 

Management and Administrative Time

Managers and HR teams may spend considerable time recording absence, arranging meetings, seeking medical information and planning a return to work.

 

Loss of Trust

Where colleagues believe an absence is being misrepresented, resentment can develop. Employers should still avoid acting on workplace rumours alone, as unverified claims may be inaccurate or unfair.

 

Possible Signs of Fraudulent Sick Leave

No single pattern proves that an employee is being dishonest. Employers should consider the full circumstances and distinguish evidence from assumption.

Possible concerns may include:

• Frequent absences immediately before or after weekends
• Repeated absence around public holidays or declined annual leave
• Different explanations being given to managers and colleagues
• Evidence suggesting the employee is working for another organisation
• Public activity that appears inconsistent with claimed physical restrictions
• Failure to follow the organisation’s absence-reporting procedure
• Refusal to engage with reasonable welfare or return-to-work discussions
• Information suggesting an injury claim has been exaggerated

Each of these may have an innocent explanation.

For example, an employee with a long-term health condition may still be able to undertake some social, physical or domestic activities. Seeing an employee outside their home does not, by itself, establish that they are fit to carry out their particular job.

 

What Should an Employer Do Before Investigating?

An external investigation should not normally be the first response to sickness absence.

Before considering surveillance or background enquiries, the employer should review its internal process.

 

Check the Absence Policy

A clear absence policy should explain:

• How employees report unplanned absence
• Who they must contact
• When self-certification or a fit note is required
• How contact will be maintained
• When absence may be reviewed
• What support is available
• How return-to-work discussions are handled
• How unauthorised absence may be addressed

The policy should be applied consistently while allowing managers to consider individual circumstances.

 

Review the Available Records

HR should examine factual information such as:

• Dates and duration of previous absences
• Reasons given by the employee
• Fit notes and occupational health recommendations
• Return-to-work meeting notes
• Relevant communication with the employee
• Any previous support or adjustments offered

Absence triggers can help identify cases that need review, but they should not automatically result in disciplinary action.

 

Speak to the Employee

The employee should usually be given an opportunity to explain the absence and discuss any support they need.

A manager may need to ask whether:

• The condition is connected to work
• The employee is receiving appropriate medical support
• A temporary adjustment could help
• A phased return is appropriate
• The absence may relate to a disability
• Occupational health advice is required

 

Consider Reasonable Adjustments

Where an employee is disabled under the Equality Act 2010, the employer may have a duty to make reasonable adjustments.

Depending on the circumstances, this could include adjusting duties, working hours, absence review points or the employee’s return-to-work arrangements.

 

Separate Facts from Workplace Rumours

Information from colleagues may justify further assessment, but an employer should not take serious action based solely on gossip, assumptions or an anonymous allegation.

The information should be assessed for credibility, relevance and whether it can be independently verified.

 

When May an Employee Absenteeism Investigation Be Appropriate?

An independent investigation may be considered where internal procedures have been followed and there is a credible reason to suspect misconduct.

Examples may include information suggesting that an employee:

• Is working elsewhere while claiming to be unable to work
• Is carrying out regular paid work through another business
• Has misrepresented their physical limitations
• Is engaging in activity that directly conflicts with a specific medical claim
• Has provided false information about the reason for absence
• Is involved in a potentially fraudulent sickness or injury claim

The proposed investigation should have a clear purpose. Employers should be able to explain:

• What concern they are trying to verify
• Why the concern is credible
• Why less intrusive measures are insufficient
• What evidence would be relevant
• How the information will be used
• Who will be allowed to see it

 

How Can Employee Absenteeism Be Investigated?

The appropriate method depends on the allegation, the employee’s role and the available information.

 

Absence Pattern Analysis

HR records can be reviewed to identify recurring dates, durations and reporting issues.

This may show a pattern requiring discussion, but patterns alone do not prove misconduct.

 

Open-Source Research

Lawfully available information may help identify undeclared business interests, directorships or publicly advertised work.

Research may include:

• Companies House records
• Public business websites
• Professional profiles
• Publicly visible social-media content
• Relevant advertising and trading information
• Other lawful open-source material

Investigators should not hack accounts, create deceptive access arrangements or attempt to obtain private messages unlawfully.

 

Background and Lifestyle Enquiries

In some cases, proportionate background research may help determine whether an employee has undisclosed secondary employment or an active business interest.

The enquiry should remain closely connected to the suspected misconduct. It should not become an unrestricted examination of the employee’s private life.

 

Covert Surveillance

Surveillance may help document activity in places where observation is lawful.

For example, it may establish whether an employee who claims to be unable to undertake a particular physical activity is repeatedly carrying out similar work elsewhere.

Surveillance evidence may include:

• A time-stamped observation log
• Photographs obtained lawfully
• Video obtained lawfully
• Details of relevant locations and activities
• A factual investigator’s report

The investigator should report only what was observed. They should not diagnose a medical condition or state that an employee is fit for work.

Medical capability decisions should be based on appropriate medical or occupational health advice.

 

Is It Legal to Conduct Surveillance on an Employee?

Employee surveillance is not automatically unlawful, but it is intrusive and must be carefully justified.

An employer considering monitoring should assess whether it is:

• For a legitimate and clearly defined purpose
• Necessary to investigate the concern
• Proportionate to the potential misconduct
• Limited in duration and scope
• Conducted using the least intrusive effective method
• Consistent with data-protection and employment obligations

The employer will normally need an appropriate lawful basis for processing personal data. Where health information is involved, additional requirements may apply because health data receives special legal protection.

A data protection impact assessment may be appropriate where the proposed monitoring is likely to create a high risk to the employee’s rights and freedoms.

Employers should also consider:

• The UK GDPR
• The Data Protection Act 2018
• The Human Rights Act 1998
• The Equality Act 2010
• Employment contracts and workplace policies
• The implied duty of mutual trust and confidence
• The Protection from Harassment Act 1997

Legal advice should be obtained where the facts are complex or disciplinary action may follow.

 

Can Surveillance Take Place at an Employee’s Home?

Observing activity that is clearly visible from a lawful public position may sometimes be possible.

However, investigators must not enter private property without authority, peer into areas where someone has a strong expectation of privacy or use unnecessarily intrusive methods.

Surveillance inside a home, through windows or in other private spaces would raise serious legal and ethical concerns.

Does the Employee Have to Be Told?

Data-protection rules generally favour transparency about workplace monitoring. However, informing an employee about a specific short-term investigation in advance may sometimes undermine a legitimate inquiry.

Any decision to use covert monitoring should be exceptional, carefully documented and limited to the suspected misconduct.

An employer should seek specialist legal and data-protection advice before proceeding.

What Evidence Can an Investigation Provide?

A professional investigation should produce objective evidence rather than conclusions based on opinion.

Depending on the assignment, a report may contain:

• A dated chronology of observations
• Time-stamped photographs or video
• Relevant public-record findings
• Details of apparent work or business activity
• Information confirming relevant locations
• A factual explanation of the methods used
• Supporting exhibits and source records

Evidence should be accurate, relevant and capable of being explained. Investigators should preserve original files and maintain a clear record of how material was collected and handled.

However, no investigation can guarantee “court-ready” or decisive proof in every case.

Evidence may support an internal HR investigation, disciplinary process, employment tribunal or legal review, but the employer and its advisers must decide how it should be used.

 

What Surveillance Evidence Does Not Prove

Video showing an employee undertaking an activity does not automatically establish that they are dishonest or medically fit to work.

The relevance depends on:

• The condition described by the employee
• The physical and mental demands of their job
• Medical advice
• The duration and frequency of the observed activity
• Whether the activity directly conflicts with a specific claim
• The employee’s explanation

The employee should normally be given a fair opportunity to respond before conclusions are reached.

 

A Three-Stage Approach to Suspected Absence Fraud

The investigation should not determine the disciplinary outcome. Its purpose is to establish facts that allow the employer to make an informed and fair decision.

 

Should Employers Use a Private Investigator?

A private investigator may be appropriate where an employer has credible intelligence but lacks the resources or expertise to verify it independently.

A professional corporate investigator should:

• Ask for a clear explanation of the concern
• Assess whether the instruction has a legitimate purpose
• Recommend proportionate methods
• Limit enquiries to relevant matters
• Explain likely outcomes and limitations
• Protect confidential information
• Keep an accurate record of investigative activity
• Report facts without exaggeration

An investigator should not accept instructions based entirely on personal curiosity, workplace gossip or a desire to examine every part of an employee’s private life.

 

Why Independent Evidence Matters

An employer may already have information suggesting misconduct, but relying on a single unverified source can create significant risk.

Independent investigation can help:

• Verify or disprove an allegation
• Reduce reliance on assumption
• Provide an accurate chronology
• Preserve relevant evidence
• Support a fair HR process
• Identify gaps requiring further assessment

An investigation may also find no evidence of wrongdoing. That remains an important result and may help prevent unfair disciplinary action.

 

How Should Investigation Data Be Protected?

Employee investigation records may contain sensitive personal information. Employers and investigators should apply suitable technical and organisational security measures.

These may include:

• Encrypted storage
• Encryption during data transfer
• Role-based access controls
• Two-factor authentication
• Secure backups
• Restricted access to original evidence
• Documented retention periods
• Secure deletion when information is no longer required
• Confidential reporting arrangements

Only people who genuinely need the information should be able to access it.

The employer should also decide how long investigation material will be retained, taking account of potential disciplinary proceedings, appeals, legal claims and data-protection obligations.

 

How Global Investigations Approaches Employee Absenteeism Cases

Global Investigations supports employers, HR teams and legal professionals where there is a credible concern about fraudulent or misrepresented sickness absence.

We normally work with a nominated contact within the organisation to preserve confidentiality and maintain a clear line of instruction.

Before accepting an assignment, we consider:

• The reason for the concern
• The evidence already available
• The employee’s role
• The specific claim being assessed
• The proposed use of the findings
• Whether less intrusive measures have been considered
• The appropriate scope and duration of the investigation

Depending on the circumstances, our business investigation services may include lawful open-source research, background enquiries or discreet surveillance.

Our reports are factual and objective. We record relevant observations without offering medical conclusions or making the final HR decision.

Global Investigations has traded since 1994 and has completed more than 12,500 successful cases. Our work is guided by discretion, legal compliance and respect for client and subject privacy.

 

Frequently Asked Questions

Can an employer investigate an employee who is off sick?

Yes, an employer may investigate a credible concern about misconduct or dishonest sickness absence. The investigation should be necessary, proportionate and conducted in accordance with employment and data-protection law.

Can an employee be dismissed for lying about sickness?

Dishonesty about sickness absence may amount to misconduct or, in serious cases, gross misconduct. However, the employer should carry out a fair investigation, consider the employee’s explanation and follow an appropriate disciplinary procedure before reaching a decision.

Is going on holiday while off sick misconduct?

Not automatically. A holiday may be consistent with recovery from some physical or mental health conditions. The employer should consider the medical circumstances, the nature of the employee’s job and whether the activity conflicts with information the employee has provided.

Can an employee work another job while on sick leave?

This depends on the employment contract, the reason for absence and the nature of the second job. Working elsewhere may be legitimate in some circumstances. It becomes more concerning where the activity conflicts with claimed medical limitations or breaches a contractual obligation.

Can an employer check an employee’s social media?

Employers and investigators may view genuinely public information where there is a lawful and relevant purpose. They should not hack accounts, obtain passwords, create deceptive access or collect excessive information unrelated to the concern.

Can a private investigator follow an employee?

Proportionate surveillance in public places may be lawful where there is a legitimate purpose and the intrusion can be justified. It should be carefully planned, limited in scope and compliant with data-protection and privacy obligations.

Can surveillance take place outside working hours?

It may sometimes be relevant to observe activity outside working hours, particularly where the allegation concerns undisclosed employment or activities inconsistent with a stated restriction. The intrusion must still be necessary and proportionate.

Can surveillance evidence be used at an employment tribunal?

Lawfully obtained surveillance evidence may be considered during legal proceedings. Its relevance, admissibility and weight depend on how it was obtained, what it shows and the circumstances of the case. Employers should seek legal advice before relying on it.

Does an investigator decide whether the employee is guilty?

No. An investigator gathers and reports facts. The employer must consider the full evidence, the employee’s response, medical information and its HR procedures before making a decision.

How long does an employee absenteeism investigation take?

The timescale depends on the allegation and the methods required. Some background enquiries can be completed relatively quickly, while surveillance may need to cover specific dates or recurring absence patterns.

Will the employee know they have been investigated?

Surveillance is intended to be discreet, but no responsible investigator should guarantee that it cannot be detected. The employer may also need to disclose relevant evidence during a disciplinary or legal process.

What information should an employer provide to an investigator?

The employer should provide information held lawfully, including the employee’s role, relevant absence dates, the nature of the concern and the specific activity that needs to be verified.

Only information necessary for the agreed investigation should be shared.

Managing Employee Absenteeism Fairly

Employee absenteeism should begin as an HR and wellbeing matter, not an assumption of wrongdoing.

Clear policies, supportive management, accurate records and appropriate occupational health input will resolve many cases without the need for external investigation.

Where credible information suggests deliberate sickness absence fraud, an independent investigation may help establish the facts. Any enquiries should remain lawful, proportionate and closely focused on the suspected misconduct.

Global Investigations supports employers who require discreet and objective assistance with complex absence concerns.

Contact Global Investigations for a confidential discussion about your circumstances, or call 0800 073 3555.