How Should Employers Investigate a Harassment or Bullying Complaint at Work? (2026 Step-by-Step Guide for UK Employers)

This guide explains how employers should investigate harassment and bullying complaints, the legal framework that applies, the risks of getting it wrong, and the practical steps organisations should take to respond effectively.

Introduction

Complaints of harassment or bullying in the workplace must be handled carefully, fairly, and promptly. When an employee raises concerns about inappropriate conduct, the employer’s response can have significant legal, reputational, and operational consequences. A poorly handled investigation will expose an organisation to claims in the Employment Tribunal, damage staff morale, and undermine trust in management.

Employers across the UK are under legal duties to provide a safe working environment and to prevent unlawful discrimination and harassment. In England and Wales, these duties arise primarily from the Equality Act 2010, health and safety obligations, and the implied contractual duty of trust and confidence between employer and employee – meaning that both parties are expected to act in a way that does not destroy the working relationship. When complaints arise, these duties translate into a responsibility to investigate properly and take appropriate action.

This article is designed for employers who are facing, or anticipate facing, a workplace complaint and may need legal guidance to manage the issue properly and reduce the risk of tribunal claims.

What Should an Employer Do Immediately After Receiving a Complaint?

The employer’s initial response can significantly influence how the situation develops. Complaints should be acknowledged promptly and handled with sensitivity and professionalism.

Early steps typically include the following:

1.Acknowledging the complaint and clarifying the allegations

The employer should confirm receipt of the complaint and seek clarification about the conduct being alleged. This involves identifying the individuals involved, relevant dates and locations, and any witnesses who may have observed the behaviour. Clarifying the allegations early ensures the investigation remains focused and fair.

2. Reminding employees about victimisation and retaliation

Employers should make it clear that retaliation against the complainant or witnesses will not be tolerated. Under the Equality Act 2010, treating someone unfavourably because they raised a discrimination or harassment complaint can amount to unlawful victimisation.

3. Considering temporary protective measures

Where necessary, employers may need to implement temporary arrangements while the investigation proceeds. This might include separating the individuals involved, adjusting reporting lines, remote working arrangements, or changes to working hours. In more serious cases, suspension on full pay may be appropriate, but it should only be used where genuinely necessary, kept under regular review, and maintained for no longer than required.

These early actions demonstrate that the employer is responding responsibly while preserving fairness for all parties.

Understanding Harassment Under the Equality Act 2010

Harassment has a specific legal definition under the Equality Act 2010. Section 26 provides that harassment occurs where a person engages in unwanted conduct related to a protected characteristic which has the purpose or effect of either violating another person’s dignity or creating an intimidating, hostile, degrading, humiliating, or offensive environment for them.

This means an employee’s perception matters even if the accused did not intend to cause offence – tribunals consider both the subjective impact on the individual and whether it was reasonable for the conduct to have that effect.

The protected characteristics covered by the Act are:

• Age
• Disability
• Gender reassignment
• Race
• Religion or belief
• Sex
• Sexual orientation

Note that pregnancy and maternity is a protected characteristic under the Equality Act 2010,and therefore employers should never ignore poor conduct related to pregnancy or maternity – such behaviour will typically amount to sex harassment or sex discrimination, and should be treated with equal seriousness.

Importantly, harassment does not need to involve repeated behaviour. A single incident can amount to harassment if it is sufficiently serious and meets the statutory definition. Employers should therefore treat complaints seriously even where the behaviour may appear isolated or informal.

Bullying and Harassment Are Not Always the Same

Workplace bullying is often discussed alongside harassment, but the two are not identical in law.

Bullying typically refers to offensive, intimidating, malicious, or insulting behaviour that undermines an individual or abuses power in the workplace. While such conduct may be unacceptable and damaging, it does not automatically fall within the statutory definition of harassment. It is worth noting that there is no standalone anti-bullying law in the UK but this does not mean employers can ignore it.

Bullying can still create serious legal risk even when it is not linked to a protected characteristic.

1.Constructive dismissal claims

Persistent bullying may amount to a breach of the implied duty of trust and confidence between employer and employee. If the employer fails to address the behaviour, the affected employee may resign and claim constructive dismissal.

2. Health and safety obligations

Employers have a duty to protect the health, safety and welfare of employees at work. Where bullying contributes to stress or mental health issues, failing to address it may expose the employer to liability.

3. Contractual and workplace culture issues

Even where no tribunal claim arises, bullying can severely damage workplace morale, productivity, and retention. Employers who ignore complaints risk creating a toxic working environment that undermines organisational performance.

For these reasons, employers should investigate bullying complaints with the same seriousness as harassment allegations.

The New Duty to Prevent Sexual Harassment

Recent legislation has significantly increased the responsibilities placed on employers in this area.

The Worker Protection (Amendment of Equality Act 2010) Act 2023, which came into force on 26 October 2024, introduced a new statutory duty requiring employers to take reasonable steps to prevent sexual harassment in the workplace.

If an employment tribunal finds that sexual harassment occurred and that the employer failed to take reasonable preventative steps, a tribunal may order a compensation uplift of up to 25%, with the amount reflecting how seriously the employer fell short of the preventative duty. In addition, the Equality and Human Rights Commission has wide enforcement powers and can investigate employers independently of any individual claim.

This development means that employers must not only respond properly to complaints but must also demonstrate that they have taken proactive preventative measures – such as clear policies, regular training, and an appropriate workplace culture that makes it safe to raise concerns.

Potential Reform

The Employment Rights Act 2025 is set to further strengthen these obligations. The duty on employers to prevent sexual harassment is expected to be elevated to require “all reasonable steps” (rather than just reasonable steps), and a new obligation not to permit third-party harassment of workers is being introduced. 

Separately, the qualifying period for unfair dismissal claims is being reduced from two years to just six months (expected to take effect from January 2027), dramatically expanding the number of employees who can bring tribunal claims following a mishandled workplace investigation. Tribunal claim time limits are also being extended from three to six months. These changes make getting workplace investigations right more important than ever.

Unsure whether your organisation has met the new sexual harassment prevention duty? Contact us for a confidential compliance review.

How Should an Employer Structure a Workplace Investigation?

A properly structured investigation is central to resolving workplace complaints fairly and lawfully.

The purpose of the investigation is fact-finding, not decision-making. The investigation gathers evidence so that a separate manager or disciplinary panel can decide whether misconduct occurred and what action, if any, should follow.

A typical investigation process involves several stages.

Appointing an impartial investigator

The investigation should be carried out by someone who is independent and appropriately senior. Ideally, the investigator should not have been involved in the events or have any personal connection with those involved. Independence strengthens the credibility of the process. In smaller organisations, or where HR personnel are themselves implicated in the complaint, it may be necessary to appoint an external independent investigator.

Defining the scope of the investigation

The investigator should clearly identify the allegations being examined and the evidence required. This prevents the investigation from drifting into unrelated issues and ensures the process remains proportionate. A useful rule of thumb is to set a target completion date at the outset and communicate this to all parties.

Separating investigation and decision-making roles

In most cases, the investigator should not be the person who decides whether disciplinary action is appropriate. If the same person investigates and decides, this could render the entire process unfair and leave the employer exposed to challenge. Having a separate decision-maker or panel helps preserve fairness and reduces the risk of bias.

The Right to Be Accompanied

A commonly misunderstood procedural right in workplace investigations concerns whether employees can bring a companion with them to meetings.

Under Section 10 of the Employment Relations Act 1999, workers have a statutory right to be accompanied at any formal disciplinary hearing or grievance meeting – that is, a meeting that may result in disciplinary action being taken. This right allows the worker to bring a trade union representative or a fellow worker.

This statutory right does not automatically apply to investigatory or fact-finding meetings. ACAS guidance makes clear that informal discussions and investigation interviews do not attract the right to be accompanied as a matter of law. However, employers are recommended to use discretion and allow accompaniment at investigation meetings as a matter of good practice, particularly where the employee has requested it and the meeting may be distressing.

Refusing a companion at a formal disciplinary hearing is a separate legal risk in itself – an employee who is improperly denied the right to be accompanied may bring a tribunal claim and receive compensation of up to two weeks’ pay.

How Should Employers Gather Evidence During an Investigation?

Evidence gathering must be careful, structured, and transparent. The goal is to establish the facts as accurately as possible.

Interviewing the complainant

The complainant should be given the opportunity to explain their concerns fully. Employers should ensure that the allegations are recorded clearly and that the complainant confirms their account. This interview forms the foundation of the investigation.

Providing the accused employee with written details of the allegations

Before interviewing the employee accused of misconduct, the employer should provide a written summary of the allegations, including key dates, witnesses, and any relevant documents. This ensures the employee understands the case against them and can respond properly.

Interviewing witnesses and collecting documentary evidence

Witness interviews should be conducted individually and recorded carefully. Documentary evidence may include emails, instant messages, meeting notes, workplace communications, CCTV footage, phone records, and attendance records. Interview notes should be shared with the interviewee where possible so they can confirm their accuracy or suggest corrections.

Maintaining accurate records is essential, particularly if the matter later becomes the subject of disciplinary proceedings or tribunal litigation.

What Happens After the Investigation Is Completed?

Once the investigation concludes, the investigator will normally prepare a written report summarising the evidence gathered and the conclusions reached. The report should clearly distinguish between findings of fact and any later disciplinary decision.

Findings on the balance of probabilities

The investigator assesses the evidence and determines whether it is more likely than not that the alleged conduct occurred. This civil standard of proof – known as the balance of probabilities. The investigator is not deciding guilt in a criminal sense, but simply whether the conduct is more likely than not to have occurred.

Referral to a decision-maker

If the findings suggest misconduct may have occurred, the matter may proceed to a disciplinary hearing. A separate manager or panel should normally decide whether disciplinary action is appropriate and what sanction, if any, should be imposed. This separation between investigation and disciplinary decision-making helps ensure fairness and procedural integrity.

The right of appeal

Employees have the right to appeal the outcome of any disciplinary or grievance process under the ACAS Code of Practice on Disciplinary and Grievance Procedures. Employers who fail to provide an appeal opportunity risk an automatic uplift of up to 25% on any tribunal compensation awarded, where a tribunal finds the failure to be unreasonable. Providing a fair appeal process is not optional – it is a key part of a defensible procedure.

What Are the Legal Risks If an Employer Mishandles a Complaint?

Employers who fail to investigate harassment or bullying complaints properly face a range of serious legal claims. Employment tribunals apply a three-part test (known as the Burchell test) to assess misconduct dismissals: 

1. Did the employer genuinely believe the employee was guilty of misconduct;
2. Was that belief based on reasonable grounds; and 
3. Was a reasonable investigation carried out before forming that belief? 

An inadequate investigation is one of the most common reasons employers lose unfair dismissal claims.

The specific claims an employer may face include the following:

Discrimination and harassment claims

Where the conduct relates to a protected characteristic, the employer may be liable under the Equality Act 2010 if they fail to respond appropriately. Employers can be held responsible for harassment carried out by their staff if they failed to take reasonable steps to prevent it. Compensation in discrimination cases is uncapped and may include awards for injury to feelings.

Victimisation claims

If an employee suffers detriment because they raised a complaint or supported a colleague who did so, the employer may face a separate claim for victimisation under the Equality Act.

Constructive dismissal claims

If an employer fails to address serious workplace issues, the affected employee may resign and claim that the employer breached the duty of trust and confidence. This type of claim does not require the employee to have been dismissed — resignation in response to an employer’s serious breach of contract is sufficient.

Increased compensation for sexual harassment cases

Where sexual harassment occurs and the employer cannot demonstrate that reasonable preventative steps were taken, a tribunal may order a compensation uplift of up to 25% under the Worker Protection Act 2023.

When Should Employers Seek Legal Advice?

While some complaints can be managed internally, certain situations benefit from early legal input.

Employers should consider obtaining legal advice where:

• The allegations involve discrimination or sexual harassment – these claims carry significant legal and reputational risk
• The complaint involves senior staff or systemic workplace concerns – repeated complaints from the same team or department may indicate deeper cultural issues within the organisation
• Disciplinary action or dismissal may result – where the investigation could lead to serious sanctions, legal advice can help ensure the process is compliant and defensible
• There is a concurrent criminal investigation – for serious allegations such as sexual assault, employers may need to consider how a police investigation affects the internal process and timeline
• An independent investigator is needed – where HR is implicated or the organisation is too small to appoint an independent internal investigator

Early guidance often helps prevent small issues escalating into complex disputes.

How JLN Can Help Employers Handle Workplace Investigations

Workplace harassment and bullying complaints require careful and balanced handling. With tribunal access expanding significantly from 2027 under the Employment Rights Act 2025, and a strengthened duty to prevent sexual harassment already in force, there has never been a more important time to ensure your investigation process is genuinely defensible.

JLN advises employers in England and Wales on workplace investigations, disciplinary processes, and employment disputes. Our team can help you:

• Protect your organisation from tribunal exposure through independent, properly structured workplace investigations
• Navigate harassment, discrimination, and victimisation risks, including meeting the new sexual harassment prevention duty
• Support employers through grievance, disciplinary, and appeal procedures in a way that is procedurally sound and legally defensible
• Review and update your anti-harassment and dignity at work policies to reflect current legal obligations, including the Worker Protection Act 2023 and Employment Rights Act 2025
• Train your managers to recognise, prevent, and appropriately respond to workplace complaints before they escalate

Early advice consistently leads to faster, lower-cost resolution and significantly reduces the likelihood of tribunal claims.

If your organisation is dealing with a harassment or bullying complaint (or wants to ensure its processes are fit for purpose before a complaint arises) contact the team at JLN for practical, confidential guidance. We offer a free initial consultation to help you understand your position and next steps.

Please email wewillhelp@jonathanlea.net or call us on 01444 708640 as a first step. Following an initial discussion, we can provide a clear scope of work, a fee estimate (or fixed fee where appropriate), and confirm any information or documentation we would need to review.

 

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This article is intended for general information only, applies to the law at the time of publication, is not specific to the facts of your case and is not intended to be a replacement for legal advice. It is recommended that specific professional advice is sought before relying on any of the information given. © Jonathan Lea Limited.