When managing a long-term or complex sickness absence, employers often face a choice about which external resource to deploy: occupational health, a private investigator, or both. Understanding what each provides, where their respective roles begin and end, and why the two approaches are complementary rather than competing is essential for making the right decision about how to manage a specific absence concern.
The short answer is this: occupational health assesses whether the employee is fit for work; private investigators assess whether the employee’s reported condition is genuine. These are different questions, and in cases where both are relevant, both tools are appropriate.
Understanding Occupational Health
Occupational health is a medical specialty concerned with the relationship between work and health. An occupational health referral in a sickness absence context produces an independent clinical assessment of the employee’s condition, its likely impact on their ability to work, whether any adjustments would support a return, and what the prognosis is for recovery.
What occupational health does not do, and is not designed to do, is investigate whether the employee’s account of their condition is accurate. The occupational health physician sees the employee in a clinical setting, takes a history, conducts an assessment, and produces a professional opinion. That opinion is based on what the patient presents and what the clinical assessment reveals. If the patient’s presentation is inconsistent with their actual activities, the occupational health report will not identify that inconsistency because the physician has no visibility of the employee’s activities outside the consultation.
Occupational health is therefore a valuable tool for managing an absence that is accepted as genuine — understanding the employee’s condition, planning a return, assessing adjustment obligations, and gathering clinical information relevant to any potential dismissal on capability grounds. It is not a tool for investigating suspected fraud.
When Investigations Are Appropriate
A private investigation is appropriate where a specific, credible concern exists that the employee’s reported absence is not genuine. That concern may arise from the indicators described in the Signs of Sickness Absence Fraud article in this series: day-of-week patterns, lifestyle activity inconsistent with the reported condition, social media posts, information from colleagues, or known activities during the absence period.
The investigation is not a response to vague management dissatisfaction with the absence. It is a structured, professional enquiry into a specific concern, designed to produce evidence that can be used in a disciplinary process if the concern is confirmed. The decision to commission an investigation should be made by a senior HR officer or in-house legal counsel, documented as a proportionate response to a specific concern, and conducted by a professional investigator who understands the applicable legal framework.
Complementary Approaches
In the most complex long-term absence cases, occupational health and private investigation play complementary and non-overlapping roles. The occupational health referral establishes the clinical picture: what the employee has reported, what the physician assessed, what the prognosis is, and what adjustments are recommended. The private investigation establishes what the employee is actually doing during the absence period: whether their activities are consistent with their reported condition, whether they are working elsewhere, and whether the clinical account they have given is consistent with their observed behaviour.
Where both produce consistent findings — the occupational health report confirms significant ongoing incapacity and the surveillance investigation confirms the employee is spending their absence at home, limiting their activity to what the condition would permit — the employer has a clear, well-documented picture of a genuine absence. Where the findings are inconsistent — the occupational health report confirms the reported condition but the surveillance investigation shows the employee is physically active in ways incompatible with that condition — the employer has a strong evidential basis for a disciplinary investigation.
Benefits of Independent Evidence
Independent investigation evidence — gathered by trained investigators using documented methodology, preserved in a form suitable for disciplinary and tribunal proceedings, and capable of being tested and challenged by the employee in a fair hearing — is the most robust form of evidence available in a sickness fraud case.
It is independent of the employer’s own assessment, removing the suggestion that the employer has simply reached the conclusion that suited them. It is contemporaneous, recorded at the time of the events it describes rather than reconstructed from memory. And it is objective, capturing what the investigator observed rather than what a manager believed they saw or what a colleague reported hearing.
These qualities make professional investigation evidence significantly more persuasive in a tribunal context than equivalent observations made by managers or colleagues, and they provide the employer with a level of confidence in the disciplinary outcome that is not achievable through internal investigation alone.
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