How to conduct an investigation in the workplace

A close up over shoulder at meeting

How do the words ‘disciplinary’, ‘capability’ or ‘grievance’ make you feel?

Chances are ‘serious’, ‘daunting’ or ‘complicated’ spring to mind, but it’s something that all managers are likely to encounter at some point and it actually need not be any of those things.

To make the process smoother, here is our 13 steps of guidance for conducting investigations:


Be clear on the scope and purpose of the investigation. What/why are you investigating? 

It might be to set out evidence of poor performance to provide clear and constructive feedback?

Or to establish facts of an alleged disciplinary concern and decide whether disciplinary action should follow.

Perhaps it is to look into an employee’s grievance and establish the facts in order to determine whether the grievance should be upheld.

Or is it necessary because an employee has raised a complaint under the Whistleblowing procedure?

The purpose of an investigation is to collect the facts and establish whether there is a case to answer and the matter should go forward to a further formal meeting.  You will need to consider early on how many people/relevant witnesses you need to speak to and how long might that take; where are they based, and will they want to remain anonymous?

Ensure you explain to everyone involved in the investigation that the matter is strictly confidential and not for wider discussion in the workplace.


Once you have determined under which process the investigation is being carried out (e.g. grievance), provide the employee with a copy of the relevant policy and procedure document. 

Check their contract or employment and Trade Union collective agreements in place (if any) for any additional process or procedure which must be followed.


Decide who will lead the investigation.

Where possible the people appointed to conduct the investigation or subsequent disciplinary, grievance hearings or appeal should be different, however this is not always possible in small businesses and ACAS will take this into account.

A nominated investigator should have experience of conducting an investigation, be of a suitable seniority and in an appropriate role within the business.

The investigator:


Collect relevant evidence. 

Keep it dated and referenced for future use in any report.

Bear in mind you have to preserve any evidence you find and may even have to suspend an employee to ensure evidence is protected.


Be thorough.

Carrying out a thorough and fair investigation sends out a good message to your employees and indicates that as an employer you will take issues seriously and will deal with matters consistently which enhances trust and confidence between the company and employees.

However, the degree of investigating carried out by the employer should be ‘reasonable in the circumstances’.

This means that the depth of the investigation necessary will depend on what is being investigated and the gravity of the issue. The more serious the issue and possible outcome (eg. dismissal), the more thorough an investigation should be.

Equally, you only need to do as much investigating as is reasonably required to prove the case either way. For example, if you are investigating an employee for fraudulent mileage claims on their travel expenses, you would only be required to identify enough instances to establish a pattern of activity and dishonesty. There is no need to trawl back through years of expense claims and provide hundreds of examples, however you would be looking to decide if the pattern is robust enough to lead to a conclusion that there is no longer trust and confidence as a result of the dishonesty.


Offer a companion.

Employees do not have a statutory right to be accompanied to an investigatory meeting, although it can sometimes be good practice to offer a companion if you feel the employee needs support during the meeting or if the allegations are particularly serious.


Act quickly.

Never delay the investigation unreasonably. The ACAS code says investigations should be carried out without undue delay and allegations should be put to an employee promptly to ensure better recollection, and that information is still fresh in the minds of those involved.


Don’t consider historic examples.

Unless there is a very good reason to consider older incidents, matters investigated should be relatively current so that those involved can remember them more accurately. The longer something is left before being investigated, the less likely it will be for the investigator to be able to carry out a fair, unbiased and thorough investigation.


Remain impartial and balanced.

There are after all two sides to every story. Keep an open mind and don’t make prejudgements. See what the evidence supports – if anything. Be open to the idea that allegations may be true, false or sometimes a combination of both! An allegation can be exaggerated or embellished but based on the truth.


Keep parties updated.

Keep both the person being investigated and the complainant informed on the progress of the investigation, particularly if there are any delays.



Evaluate the evidence you have collected and make a decision on whether the evidence presented supports the allegations made or not. Explain why.


Report your findings.

Document your findings and summarise them in a report. There is no legal guidance or set format for an investigatory report, but it is very good practice to set out your findings in a formal document with appendices to include copies of information collected and used, in case it is needed in the future.

Provide an outcome letter with your recommendations on whether there is or isn’t a case to answer and provide a copy of the report and supporting evidence (check who should have a copy of the report depending on the outcome).  You can also make recommendations on potential solutions, for example if mediation might be beneficial to resolve matters between two employees.


Investigations can be very simple or complex depending on the nature of the case, and sometimes disciplinary and grievance investigations can run concurrently. As with any formal procedure and depending on the gravity of the issue, consider whether to keep the investigation in-house or bring in an independent consultant. If your budget allows, there can be real relief in using an efficient, impartial advisor to handle any conflict, keep the investigation on track and within guidelines.

Charlotte Allfrey