Handling grievances in the United Kingdom
Reviewed by Mellow Editorial Team, HR & payroll content team
Handling a workplace grievance in the UK means following a clear, consistent process — ideally one that mirrors the ACAS Code of Practice on Disciplinary and Grievance Procedures. Failing to do so does not automatically make a dismissal or decision unlawful, but an employment tribunal can adjust any compensation award by up to 25% if either party unreasonably ignores the Code.
This article is general information, not legal advice. For your specific situation, consult an employment solicitor or HR professional.
What counts as a grievance
A grievance is any concern, complaint or problem a worker raises formally with their employer. Common examples include:
- Concerns about pay, working hours or working conditions
- Bullying, harassment or discrimination
- Disputes about how a policy has been applied
- Problems with a manager's behaviour or a colleague's conduct
Grievances can also arise from changes to employment terms — for instance, if a restructure affects someone's role or hours. Under the Employment Rights Act 2025, day-one rights are broader than they were previously, so workers are better protected from the outset of employment. That raises the stakes for getting the process right.
The ACAS Code in practice
The ACAS Code of Practice sets out the expected standard. It is not legally binding in itself, but employment tribunals treat it as the benchmark. The core steps are:
1. Receive the grievance in writing. Encourage the employee to set out their complaint clearly. You do not need a formal form, but a written record matters.
2. Investigate promptly and fairly. Appoint someone who was not involved in the underlying complaint to gather the facts. Speak to relevant witnesses, review any documents, and keep notes throughout.
3. Hold a grievance meeting. Invite the employee to a formal meeting, giving them reasonable notice. Under the Employment Relations Act 1999, they have a statutory right to be accompanied by a trade union representative or a fellow worker. The chosen companion can address the meeting and confer with the employee, but cannot answer questions on their behalf.
4. Reach a decision and communicate it in writing. Explain your findings, the outcome and the reasoning. Do this without unreasonable delay — within five working days where possible, though complex cases may take longer.
5. Offer the right of appeal. The employee must be told they can appeal the outcome. Appeals should ideally be heard by a more senior manager who was not involved in the original hearing.
Keeping the process fair
Consistency is essential. Apply the same process to everyone, regardless of seniority, length of service or the nature of the complaint. Document every stage: the written grievance, investigation notes, hearing notes, the outcome letter and any appeal correspondence.
Confidentiality matters too. Keep the details of the grievance on a need-to-know basis. Unnecessary disclosure can damage working relationships or, in serious cases, expose you to a data protection complaint.
Where a grievance overlaps with a disciplinary matter — for instance, an employee raises a grievance against a manager during their own disciplinary process — you will need to decide whether to run the processes concurrently or pause one while the other concludes. There is no single correct answer; use judgement, act proportionately, and document your reasoning.
Grievances about discrimination and protected characteristics
Where a grievance involves a protected characteristic under the Equality Act 2010 — such as age, disability, race, religion, sex or sexual orientation — treat the matter with additional care. Ensure the investigator is trained to identify less obvious forms of discrimination, including indirect discrimination and harassment.
If the grievance is upheld, consider whether systemic changes are needed, not just individual remedies. Failing to address a pattern of behaviour can leave you exposed to further claims.
When a grievance cannot be resolved internally
If your internal process does not resolve matters, the employee may choose to raise an early conciliation notification with ACAS before bringing a tribunal claim. Early conciliation is a mandatory step before most employment tribunal claims can proceed. The process is free and confidential, and a conciliator will try to help both parties reach a settlement without going to a formal hearing.
Keeping records of your process — and evidence that you followed the ACAS Code — puts you in a much stronger position at this stage. Tribunals look at whether the employer acted reasonably throughout, not just whether the outcome was technically correct.
A note on prevention
Most grievances are easier to prevent than to resolve. Regular one-to-ones, clear policies, accessible management and prompt action on early warning signs all reduce the likelihood of a formal complaint. When concerns are raised informally, take them seriously — an informal resolution that satisfies both parties is almost always preferable to a formal process.
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