Disciplinary procedures: following the ACAS Code
The ACAS Code of Practice on Disciplinary and Grievance Procedures is not law, but departing from it without good reason significantly increases the risk of losing a tribunal claim. Tribunals can increase a compensatory award by up to 25% where the employer has unreasonably failed to follow the Code. Understanding what the Code requires — and building it into your disciplinary process — is foundational HR compliance.
Before the formal process: the investigation
Before a disciplinary meeting is held, there must be a reasonable investigation. The investigation should establish the facts: what happened, when, who was involved, what evidence exists. The investigation is not the same as the hearing — the investigator gathers evidence, the hearing considers it. In small organisations, the same person often does both, but they should be conceptually separate steps.
Step 1: Inform the employee in writing
The employee must be told in writing that they are subject to a formal disciplinary process, what the allegation is, and that they are invited to a disciplinary hearing. The letter should explain their right to be accompanied (by a colleague or trade union representative), give them adequate time to prepare, and attach any evidence to be considered at the hearing.
Step 2: The hearing
The hearing must give the employee a genuine opportunity to tell their side of the story. Avoid reaching a decision before the hearing — going through the motions of a hearing while having already decided the outcome is a common and costly error. Listen, ask questions, consider the employee's explanation.
Step 3: The decision
After the hearing, take time to consider. The decision should be proportionate: a first minor misconduct offence warrants a written warning, not dismissal. The Code recommends a staged approach: first written warning, final written warning, and then dismissal for repeated conduct issues. Summary dismissal for gross misconduct bypasses the staged approach, but the allegation must genuinely constitute gross misconduct.
Step 4: Communicate the decision in writing
Tell the employee the decision in writing. Explain the reasons. Confirm the right of appeal. For a warning, specify how long it will remain on record (typically 6 to 12 months for a written warning, up to 2 years for a final written warning).
Step 5: The appeal
The employee has a right to appeal any disciplinary decision. The appeal should be heard by a more senior person (or someone not involved in the original decision). The appeal is a genuine reconsideration, not a rubber stamp.
The ACAS Code applies to disciplinary and dismissal processes generally, regardless of length of service — automatically unfair dismissals (such as for whistleblowing or asserting a statutory right) can be challenged from day one, and a tribunal can adjust awards for failing to follow the Code. Note that ERA 2025 did not introduce a day-one unfair dismissal right: the qualifying period stays at two years for now and is planned to drop to six months for dismissals on or after 1 January 2027. Following a fair process is good practice well ahead of that change. See day one unfair dismissal rights for the full context.
Mellow's disciplinary module guides managers through each step, stores the correspondence, and generates the required letters. [Start a free trial →](https://mellowhr.com/register)