Getting workplace investigations right: practical tips for employers

Workplace investigations have become an increasingly important part of organisational risk management. The strengthened harassment obligations being introduced by the Employment Rights Act 2025 mean that employers must not only respond appropriately to concerns when they arise, but also demonstrate that complaints are investigated effectively.

At the same time, AI tools are making it easier for employees to submit detailed and more sophisticated complaints, increasing the volume and complexity of issues that organisations may need to address. Against this backdrop, it is more important than ever for employers to have investigation processes that are fair, proportionate and capable of withstanding scrutiny.

While no two investigations are the same, we outline six common principles that can help employers establish a robust and credible process from the outset:

1. Be clear about what you are investigating

Preparation is the key to any successful investigation. A common mistake is to move too quickly into fact-finding without first taking the time to define the issues properly.

Employers should be clear about the purpose of the investigation. Is it to investigate a grievance, allegations of misconduct, concerns raised through a whistleblowing process, or wider cultural issues? The answer will shape the scope, process and eventual outcome.

It is also important to be clear about what is not being investigated. While investigations should be capable of adapting if new information comes to light, clarity at the outset helps avoid confusion, manages expectations and maintains confidence in the process.

2. Choose the right workplace investigator

One of the first decisions is whether the investigation should be conducted internally or by an external investigator.

There is no single correct answer. Many routine workplace investigations can be handled effectively by appropriately trained internal HR professionals or managers. However, employers should consider appointing an external investigator where:

• allegations involve senior leaders;
• independence may be questioned;
• there are concerns about conflicts of interest;
• the issues are particularly sensitive or high-profile;
• specialist expertise is required; or
• an organisation lacks the capacity or resource to conduct the investigation properly.

An investigator must be, and be seen to be, impartial. Many investigations falter not because of the conclusions reached, but because participants lose confidence in the independence of the process. Even where an internal investigator is technically capable of conducting the investigation, employers should consider whether an external appointment would provide greater credibility and reassurance to those involved.

3. Develop clear terms of reference

Key to a robust and credible investigation is ensuring there are clear terms of reference which define the scope and purpose from the outset.

They should set out:

• the issues to be investigated;
• who will conduct the investigation;
• the applicable policies or procedures;
• the expected methodology;
• the anticipated timeframe;
• the expected outcome;
• how any new issues that emerge during the investigation will be dealt with; and
• who will receive the investigation report.

Good terms of reference help investigators understand their remit and give participants confidence that the process is structured and fair. They also help prevent 'scope creep' and provide a useful reference point if concerns later arise about the conduct of the investigation.

4. Be clear about the expected outcome

Employers should decide at the outset what they want the investigator to produce. Do you want the investigator simply to undertake a fact-finding investigation? Or should they make recommendations?

The answer will often depend on what follows the investigation. For example, where the report will inform a subsequent disciplinary process, the investigator may simply be asked to establish the facts, leaving any disciplinary decision to the hearing manager.

Sometimes a pure fact-finding report is challenging, because there may be circumstances in which the investigator is faced with conflicting evidence. In this case, investigators should be encouraged to give a view on the balance of probabilities as to which version of events is more likely to be true. Reports that simply set out competing accounts can make it challenging for organisations to decide what to do next.

The output of the investigation will also be important to determine up front. Will the investigator provide a detailed written report appending all interview notes and other evidence collected? Or is the purpose of the investigation more general, such that it may be sufficient to report back to the Board in person along with a written summary of findings?

5. Confidentiality and anonymity

As far as possible, workplace investigations should be conducted confidentially and information shared on a need to know basis only. This helps protect all individuals involved and reduces the risk of gossip, retaliation or unnecessary reputational damage. Confidentiality expectations should be explained clearly to participants from the outset.

Requests for anonymity require more careful consideration. In certain cases, particularly those involving allegations of bullying, harassment or sexual misconduct, individuals may have genuine concerns about being identified. However, anonymity can create challenges for procedural fairness and may limit the investigation's ability to test evidence properly.  As a result, anonymity should be permitted in exceptional circumstances only, in keeping with Acas guidance on investigations at work.

For a full discussion of this topic, see: Managing anonymity in workplace investigations

6. Communicate regularly and provide support

Participants in investigations are more likely to engage constructively where they feel informed, supported and treated with respect. One of the most frequent causes of dissatisfaction in an investigation is a lack of communication.

Participants should understand:

• what stage the investigation has reached;
• what is expected of them;
• anticipated timescales; and
• where they can access support.

Where unexpected delays occur, these should be explained and updates provided where appropriate. Keeping participants informed is particularly important because lengthy delays increase stress for those involved, can affect recollection of events and may ultimately undermine confidence in the process.

Employers should also think proactively about wellbeing of all participants, including the subject of any allegations. Depending on the circumstances, support might include access to employee assistance programmes, workplace adjustments or other welfare measures.

Key takeaways

When concerns are raised, there can be a natural temptation to move straight into evidence-gathering and witness interviews. However, the success of a workplace investigation is often determined long before the first witness is spoken to.

Careful planning, a clearly defined scope, an appropriate investigator and effective communication can all make the difference between a process that inspires confidence and one that attracts criticism.

This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Farrer & Co LLP, July 2026