Pillar Guide · Updated July 2026
UK Workplace Grievance Procedure: A Practical Guide for 2026/27
Knowing how to raise a formal grievance correctly can materially change the outcome of a workplace dispute — and, if the matter later reaches an employment tribunal, can directly affect the compensation awarded. This pillar guide explains the ACAS Code of Practice that governs fair grievance handling, how to write an effective grievance letter, what happens at the investigation and hearing stage, your statutory right to be accompanied, the appeals process, and why raising a grievance properly — before resigning or escalating — matters so much for any later tribunal claim.
What Is a Grievance
A grievance is a formal concern, problem or complaint raised by an employee with their employer about something happening at work. Common triggers include treatment by a manager or colleague, pay and terms and conditions disputes, excessive workload, bullying or harassment, discrimination, or breach of a company policy. Formally raising a grievance, typically in writing, triggers the employer’s obligation to investigate and respond following a fair process, which is distinct from simply mentioning a concern informally in passing conversation.
The ACAS Code of Practice
The ACAS Code of Practice on Disciplinary and Grievance Procedures sets the minimum fairness standard expected of both employers and employees in Great Britain. Although not itself a statute, employment tribunals are required to take the Code into account in relevant cases and can adjust compensation up or down by up to 25% depending on whether either party unreasonably failed to follow it — giving the Code real practical weight despite its technical status as guidance rather than binding law.
Writing a Grievance Letter
Check your employer’s own grievance policy first, usually found in the staff handbook or intranet, since it may specify a preferred form or route, although the underlying ACAS Code principles apply regardless of the specific internal process. Put the grievance in writing, stating clearly and specifically what the complaint is about, the relevant dates, the people involved, and the outcome you are seeking.
Keep the tone factual and specific rather than heavily emotional, and retain a copy of the letter together with any supporting evidence — emails, messages, and names of potential witnesses — for your own records throughout the process.
Investigation and Hearing
The employer should acknowledge the grievance promptly and arrange a grievance meeting without unreasonable delay, at which you can explain your complaint and present supporting evidence. Depending on complexity, the employer may investigate — gathering evidence and interviewing witnesses — before or after this meeting, and should confirm the outcome and reasoning in writing within a reasonable period. The ACAS Code does not fix statutory deadlines for each stage, but unreasonable delay at any point is itself something a tribunal will weigh if the matter later escalates.
Right to Be Accompanied
Under the Employment Relations Act 1999, workers have a statutory right to be accompanied at a formal grievance hearing (and disciplinary hearings) by a fellow worker, a trade union representative, or an official employed by a trade union, provided the grievance concerns a fairly broadly defined statutory duty covering most genuine formal grievances. The companion may address the hearing and confer with the employee but generally cannot answer questions on their behalf. Employers must reasonably accommodate the request, including rearranging the date if the chosen companion cannot attend originally.
The Appeal Process
The ACAS Code expects employers to offer a right of appeal where the grievance outcome does not resolve the employee’s concern satisfactorily. Wherever practical, the appeal should be heard by someone more senior who was not involved in the original decision, to ensure a genuinely fresh review rather than a rubber-stamp of the initial outcome. Failing to offer, or properly conduct, an appeal is itself a factor a tribunal weighs in assessing ACAS Code compliance in any later claim.
Grievance vs Disciplinary
A grievance is raised by an employee about the employer, a colleague, or workplace conditions; a disciplinary process is initiated by the employer against an employee over alleged misconduct or performance concerns. The two processes sometimes run in parallel — for example, a grievance about how a disciplinary process is being conducted, or a grievance about a colleague that itself triggers a separate disciplinary investigation into that colleague. Employers should generally not simply merge or set aside one process in favour of the other without good reason, since each carries distinct procedural fairness requirements under the ACAS Code.
The 25% Tribunal Uplift
Where a tribunal finds that either the employer or the employee unreasonably failed to follow the ACAS Code — for example, an employer skipping a proper investigation, or an employee resigning without raising a grievance first — compensation in a relevant successful claim can be adjusted up (against a non-compliant employer) or down (against a non-compliant employee) by as much as 25%. This makes following the Code a matter of direct financial consequence, not merely good practice, for both sides of a dispute.
When to Escalate
If the internal grievance and appeal process does not resolve the matter, the next step (for disputes that amount to a legal claim, such as discrimination, unfair or constructive dismissal, or unlawful deductions from wages) is usually ACAS Early Conciliation, a mandatory precursor to most employment tribunal claims, followed by the tribunal claim itself if conciliation does not resolve the matter. Completing the internal grievance process properly first, rather than skipping straight to a claim, both improves the prospects of an early resolution and protects against a tribunal compensation reduction for non-compliance with the ACAS Code.