The ACAS disciplinary procedure, step by step

The ACAS Code of Practice on Disciplinary and Grievance Procedures is statutory. Failure to follow it allows employment tribunals to adjust awards by up to 25% in the employee's favour. From January 2027, with the unfair dismissal qualifying period dropping to six months and the compensation cap removed, following the Code correctly becomes more important than ever.

Step 1: Investigate

Conduct a reasonable investigation before initiating a disciplinary process. Reasonable means proportionate to the seriousness — a minor matter needs a brief fact-finding; a gross misconduct allegation needs a thorough investigation.

• Gather documentary evidence.
• Interview witnesses, keep notes.
• Allow the employee to be interviewed if appropriate at the investigation stage.
• The investigator and the disciplinary decision-maker should ideally be different people.

Step 2: Written invitation to the hearing

Write to the employee inviting them to a disciplinary hearing. The letter must:

• State the alleged misconduct clearly and specifically.
• Make clear that the hearing may result in disciplinary action, including (where relevant) dismissal.
• Confirm the right to be accompanied by a trade union representative or work colleague.
• Enclose all documentary evidence the employer intends to rely on.
• Give the employee reasonable notice to prepare — typically at least 5 working days.

Step 3: Right to be accompanied

The right to be accompanied is statutory. The companion can be:

• A trade union official (whether or not the workplace recognises that union); or
• A work colleague.

The companion can address the hearing, sum up, respond to views, and confer with the employee — but cannot answer questions on the employee's behalf.

Step 4: The hearing itself

• Run by an impartial chair (typically a manager not involved in the investigation).
• Notes should be taken.
• Present the evidence and allow the employee to respond.
• Adjourn before reaching a decision — never decide at the hearing itself.
• Consider mitigation, length of service, previous record.

Step 5: Decision and outcome letter

Write to the employee with:

• The decision and reasoning.
• The evidence considered.
• Any sanction imposed (warning, dismissal, etc.).
• The duration of any sanction (how long it remains "live").
• The right of appeal, with timescale and who to appeal to.

Step 6: Appeal

Always offer a right of appeal. It must be heard by:

• A more senior manager than the one who took the original decision; or
• An independent person if seniority makes that impractical.

The appeal should consider whether the original process was fair and whether the decision was reasonable.

The sanctions ladder

In order of seriousness:

1. Informal discussion (not a formal sanction).
2. First written warning (typically live for 6–12 months).
3. Final written warning (typically live for 12 months).
4. Dismissal with notice.
5. Summary dismissal without notice — gross misconduct only.

What the ACAS Code does not require

The Code is not a rigid script. It does not require a particular form of words, and a minor procedural deviation is not automatically fatal. What matters is that the process is fair, reasonable and proportionate.

Official source: ACAS Code of Practice on Disciplinary and Grievance Procedures.