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How to write an investigation report

Following an investigation into an incident at work, it's sensible to record the findings in a written report.

A report will set out everything that has and has not been established - getting everything down will make it harder for anyone to argue that an investigation has been selective with evidence and therefore biased.

Writing a report

A structured approach to writing a report will help investigators cover all the facts, outline any missing information and put forward any mitigating circumstances too.

As the report will be read by all parties concerned, it's important that the investigator uses objective language, avoids jargon and nicknames, and sticks to the facts, including all the evidence that was gathered.

Reaching a conclusion

Evidence in the report can be arranged into three groups:

  • uncontested facts - which can be reported as facts
  • contested facts - investigators should determine 'on the balance of probabilities' what took place
  • unsubstantiated claims - investigators can recommend further investigation or say that they were unable to reach a conclusion.

An investigator should endeavour to reach conclusions about what did or did not happen, even when evidence is contested or contradictory.

Unlike criminal proceedings in which the standard of proof is 'beyond reasonable doubt', an investigator only needs to decide that 'on the balance of probabilities' an incident is more likely to have occurred than not.

This makes it easier for investigators to reach a conclusion - but they should also explain why they have reached their conclusions.

Making recommendations

On the basis of this, it's also common for an investigator to make a recommendation, about whether formal action, informal action or no further action should be taken.

An investigator should not suggest a possible sanction or prejudge what the outcome to a grievance of disciplinary hearing might be.

Acas publications and services

Free investigation report templates, as well as investigation plan templates, sample letters informing employees of an investigation or inviting employees to an investigation meeting, are available to download from the Acas Carrying out investigations in the workplace page.

Acas has published pdf icon Conducting workplace investigations [573kb], guidance that outlines the essential decisions and actions that employers must and should make when undertaking an investigation.

Acas experts can visit your organisation and help you address a range of issues related to conducting investigations; see Disputes and mediation: how Acas can help for more information.

Practical training is also available on Investigations, Discipline and grievance, improving Skills for supervisors, Dispute resolution and Handling difficult conversations.

For free, impartial advice and guidance visit Acas Helpline Online.

Visit the Acas Training Courses, Workshops and Projects area for more information.


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