Running a fair disciplinary process in the United Kingdom
Reviewed by Mellow Editorial Team, HR & payroll content team
A fair disciplinary process in the UK follows the ACAS Code of Practice on Disciplinary and Grievance Procedures. Employers who skip steps or act inconsistently risk unfair dismissal claims at an Employment Tribunal — and a tribunal can uplift any award by up to 25% if an employer unreasonably fails to follow the Code.
Why the ACAS Code matters
The ACAS Code is not legally binding, but employment tribunals take it into account when deciding whether a dismissal or disciplinary sanction was fair. Following it does not guarantee you will win a tribunal claim, but departing from it without good reason is difficult to defend.
The Employment Rights Act 2025 has strengthened day-one rights for employees, which makes procedural fairness even more important than it was before. You can no longer rely on a short qualifying period to protect you from certain claims, so getting the process right from the start matters more.
The core steps in a fair procedure
1. Investigate first
Before you do anything else, carry out a reasonable investigation. That means gathering evidence — emails, timesheets, witness accounts — and, where appropriate, speaking to the employee informally. The depth of the investigation should be proportionate to the seriousness of the allegation. A minor lateness issue requires far less investigation than an allegation of fraud.
Consider whether to suspend the employee during the investigation. Suspension should not be a default or a punishment. Use it only where there is a genuine risk to the business, its people or its evidence — for example, where the employee might interfere with witnesses. Any suspension should be on full pay unless your contract explicitly allows unpaid suspension, and it should be kept as short as possible.
2. Invite the employee to a disciplinary hearing in writing
Once you have enough evidence to justify a hearing, send a written invitation. The letter should:
- set out the nature of the alleged misconduct or performance issue
- include copies of the evidence you intend to rely on
- give the employee reasonable notice (usually at least 48 hours, though more is better for serious matters)
- remind the employee of their right to be accompanied
The right to be accompanied means the employee can bring a trade union representative or a colleague. They cannot bring a solicitor to a disciplinary hearing, though you can permit it if you choose.
3. Hold the hearing fairly
At the hearing, present your case, then give the employee a genuine opportunity to respond. Listen. Do not treat the hearing as a formality where the outcome is already decided. Ask questions, consider explanations, and keep notes — a written record protects both parties.
Adjourn before you reach a decision. This demonstrates that you have genuinely reflected on what you heard rather than walking in with a predetermined outcome.
4. Communicate the outcome in writing
After the hearing, write to the employee with your decision. Be clear about:
- what sanction, if any, you are imposing
- the reasons for that decision
- any improvement required and over what timescale
- the employee's right to appeal
Typical sanctions run from a first written warning through to a final written warning and, at the most serious end, dismissal. Gross misconduct — theft, violence, serious harassment — can justify summary dismissal (dismissal without notice), but only after a proper process, not as an automatic consequence of the allegation.
5. Run a genuine appeal
The appeal is not a box-ticking exercise. It should be heard by a different manager where possible — ideally someone more senior than the person who conducted the original hearing. The appeal manager should review the evidence afresh, consider whether the original process was fair, and be willing to overturn the decision if warranted. Confirm the appeal outcome in writing.
Consistency and proportionality
Two principles run through every stage: consistency and proportionality. If you dismissed one employee for a particular act of misconduct but only warned another employee for the same behaviour, you need a clear, documented reason for the difference. Without one, the dismissed employee has a strong argument that their treatment was unfair.
Proportionality means matching the sanction to the severity of the conduct and the employee's record. A first-time minor infraction rarely justifies dismissal. Consider the employee's length of service, any mitigating circumstances they raised, and whether their conduct caused actual harm.
Keeping records
Document every step. Investigation notes, invitation letters, hearing notes, decision letters, appeal correspondence — retain them all. If a claim does reach an Employment Tribunal, you will need to demonstrate exactly what happened and when. Good records are your clearest evidence that the process was thorough and fair.
Where your business uses a payroll or HR platform to manage employment records, keeping disciplinary correspondence in the same system makes that audit trail easier to maintain — and harder to lose.
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This article provides general information about UK employment practices. It is not legal advice. For guidance on specific situations, consult a qualified employment law solicitor or contact ACAS directly.
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