How to Handle a Grievance: UK ACAS Process

When an employee raises a concern that they cannot resolve informally, UK employment law expects the employer to follow a structured grievance procedure. The reference standard is the ACAS Code of Practice on Disciplinary and Grievance Procedures, issued under section 199 of the Trade Union and Labour Relations (Consolidation) Act 1992. Failing to follow it does not attract a direct fine, but a Tribunal can adjust an award up or down by up to 25% under section 207A of TULRCA 1992 if a party has unreasonably failed to comply with the Code. This guide walks through how to handle a grievance correctly, in the order steps actually need to happen.

Step 1. Try Informal Resolution First

Before opening a formal grievance, the ACAS Code recommends informal resolution where possible. A quiet conversation between the employee and their line manager often resolves the issue without escalation. This step:

• Costs nothing and damages no relationships.
• Should be documented internally even if no further action is taken.
• Should not be used to suppress a legitimate concern — if the issue is serious (harassment, discrimination, whistleblowing), formal procedures must follow.

Source — ACAS Code of Practice on Discipline and Grievance: https://www.acas.org.uk/acas-code-of-practice-on-disciplinary-and-grievance-procedures

Step 2. The Grievance is Raised in Writing

The employee should put their grievance in writing — usually addressed to their line manager or, if the manager is the subject of the grievance, to a more senior manager or HR. The written statement should include:

• A clear description of the concern.
• The relevant dates and people.
• The outcome the employee is seeking.

The employer should acknowledge receipt promptly and give the employee an indication of timescales.

Step 3. Set Up the Grievance Hearing

The Code requires the employer to:

• Hold the meeting without unreasonable delay.
• Give the employee enough time to prepare — typically 5 working days from notice of the meeting.
• Notify the employee of their right to be accompanied at the meeting.

The right to be accompanied is statutory, not just code-based — it derives from section 10 of the Employment Relations Act 1999. The employee can be accompanied by:

• A trade union official.
• A trade union representative.
• A fellow worker.

The companion can address the meeting, sum up the employee’s case, and confer privately with the employee — but cannot answer questions on the employee’s behalf.

Source — Employment Relations Act 1999, s.10: https://www.legislation.gov.uk/ukpga/1999/26/section/10

Step 4. Conduct the Hearing Properly

At the meeting:

• Allow the employee to explain their grievance fully.
• Take notes (or have a note-taker) — these become the formal record.
• Allow the employee to call witnesses or refer to documents.
• Adjourn if needed to investigate further claims.
• Do not commit to an outcome on the spot unless the issue is clearly resolvable.

The hearing should be chaired by a manager who is impartial — not someone who has been involved in the underlying issue. Where this is not possible (e.g., small employer), it should still be a person who has not made up their mind in advance.

Step 5. Investigate Where Necessary

For serious or factual grievances (e.g., bullying, discrimination, safety), an investigation is normally required. The investigation should:

• Be conducted by a different person from the one chairing the hearing where possible.
• Interview relevant witnesses.
• Examine relevant documents and records.
• Be completed within a reasonable time — typically 2 to 4 weeks for most cases.

The investigator’s report is a written summary of findings of fact, not a recommendation on outcome (which is the chair’s decision).

Step 6. Communicate the Outcome in Writing

Once the chair has reviewed the evidence, the outcome must be:

• Communicated in writing to the employee.
• Without unreasonable delay — typically within 5–10 working days of the hearing.
• State the decision and the reasons for it.
• Inform the employee of their right of appeal and how to exercise it.

The decision letter should be balanced and factual. It should address each element of the grievance and explain whether each is upheld, partially upheld, or not upheld, and why.

Step 7. Handle the Appeal

The employee has the right to appeal under the ACAS Code. The appeal should be:

• In writing stating the grounds.
• Heard by a different manager from the original hearing — ideally more senior.
• Conducted promptly — typically within 4 weeks.
• The decision communicated in writing.

Appeals can be a full re-hearing or a review of the original decision. Either approach is acceptable provided the employee has a fair opportunity to present their case.

Step 8. Document the Process

Throughout, keep:

• The original written grievance.
• Notes/minutes of every meeting.
• Investigation report (if any).
• Witness statements (if any).
• Outcome letter.
• Appeal correspondence and outcome.

These records are essential if the matter goes to Tribunal. They are also subject to the subject access right under the UK GDPR — the employee can request a copy of all data held about them, including grievance records.

Step 9. ACAS Early Conciliation Before Tribunal

If the employee is dissatisfied with the outcome and considers Tribunal proceedings, they must first contact ACAS for Early Conciliation under section 18A of the Employment Tribunals Act 1996. ACAS will offer a 6-week conciliation period (extendable by up to 14 days by mutual agreement) during which a settlement can be explored.

If conciliation succeeds, a binding settlement agreement is signed (form COT3). If it fails, ACAS issues a certificate which the claimant must include with their Tribunal claim.

Source — ACAS Early Conciliation: https://www.acas.org.uk/early-conciliation

Step 10. Common Mistakes — Gyoseishoshi View

• Skipping the right to be accompanied. This is statutory, not optional. Failure can lead to a Tribunal award up to 2 weeks’ pay.
• Chair has prior knowledge of the issue. Choose impartiality wherever possible. Even small employers can ask an external HR adviser to chair.
• Treating a grievance as a complaint about the company’s policies. The employee may simply be unhappy with the policy. The grievance procedure is for personal grievances; the policy review process is separate.
• Delaying the outcome letter. A 6-week delay between hearing and outcome is unreasonable. The Tribunal will take notice.
• Not offering an appeal. The Code requires the right of appeal. Skipping this stage exposes the employer to the 25% Tribunal uplift on any subsequent award.
• Treating informal mention as formal grievance — and vice versa. Be clear with the employee whether the matter is formal or informal. If formal, follow the full process.
• Making promises during the hearing. A hearing is for listening, not deciding. Save the outcome for the formal letter.
• Mixing grievance and disciplinary processes. If the grievance is against another employee, that may trigger a separate disciplinary process against that employee — but the two procedures should be kept distinct, with separate decision-makers.

Step 11. Specific Categories of Grievance

Some grievances trigger additional duties:

• Discrimination (Equality Act 2010) — failure to investigate adequately can give rise to a separate claim of victimisation. The investigation should specifically address the protected characteristic.
• Whistleblowing (Public Interest Disclosure Act 1998 / ERA 1996 Part IVA) — protected disclosures attract enhanced protection. The employee cannot be subjected to detriment for raising the issue.
• Health and safety concerns — under the Employment Rights Act 1996, s.44, an employee cannot be subjected to detriment for raising a health-and-safety concern.
• TUPE-related concerns — see related article on TUPE 2006.

Step 12. Settlement and Confidentiality

If the employer concludes the grievance has merit but the relationship cannot be saved, a settlement agreement may be appropriate. To be enforceable, settlement agreements must:

• Be in writing.
• State they are settlement agreements within the meaning of the relevant Act.
• Identify the specific complaints being settled.
• Be received by the employee with independent legal advice from a relevant adviser.
• Have the adviser’s professional indemnity in place.

Settlement agreements typically include a confidentiality clause; however, NDAs cannot lawfully prevent the employee from reporting whistleblowing matters or criminal matters to the police or regulator.

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Disclaimer

This article provides legal information, not legal advice. MmowW Scrib🐮 is a document preparation service operated by a licensed Gyoseishoshi (行政書士) office in Japan. We are not UK solicitors or barristers.

Sources

• ACAS Code of Practice on Discipline and Grievance: https://www.acas.org.uk/acas-code-of-practice-on-disciplinary-and-grievance-procedures
• Employment Relations Act 1999, s.10: https://www.legislation.gov.uk/ukpga/1999/26/section/10
• Trade Union and Labour Relations (Consolidation) Act 1992, s.207A: https://www.legislation.gov.uk/ukpga/1992/52/section/207A
• ACAS Early Conciliation: https://www.acas.org.uk/early-conciliation