ACAS Disciplinary Procedure: A Practical Guide for UK Employers

Most disciplinaries that end up at tribunal don't fail because the employee was innocent. They fail because the employer skipped a step. A manager sent a "final" warning without a hearing. Someone dismissed an employee on the same call they told them there was a problem. A hearing went ahead while the accused was signed off sick, with no attempt to reschedule. Each of those is a procedural mistake, and each of them can lift an award by 25% under section 207A of the Trade Union and Labour Relations (Consolidation) Act 1992.

The ACAS Code of Practice on Disciplinary and Grievance Procedures is short. It runs to fewer than 20 pages. But tribunals treat it as the minimum standard of fairness, and getting it right is the difference between a defensible outcome and an expensive one. This guide walks through the procedure the way an HR manager would actually run it, with the practical detail that the Code itself doesn't spell out.

What the ACAS Code actually is (and isn't)

The ACAS Code of Practice is statutory guidance issued under section 199 of the Trade Union and Labour Relations (Consolidation) Act 1992. It is not law in the strict sense. You cannot be sued for breaching the Code itself. But an employment tribunal must take it into account when deciding whether a dismissal was fair under the Employment Rights Act 1996, and unreasonable failure to follow it allows the tribunal to adjust compensation by up to 25% either way.

The Code applies to conduct and performance issues. It does not apply to redundancies or the non-renewal of fixed-term contracts. It also does not cover collective grievances. There is a separate, longer ACAS Guide to Discipline and Grievances at Work that sits alongside the Code, and I'd treat that as your practical playbook rather than the Code itself.

The core principles the Code expects you to follow

Boil the Code down and you get six things:

• Raise and deal with issues promptly, and don't unreasonably delay meetings, decisions, or the confirmation of those decisions.
• Act consistently.
• Carry out any necessary investigations to establish the facts.
• Inform the employee of the problem and give them a chance to respond before any decision is made.
• Allow the employee to be accompanied at any formal disciplinary meeting.
• Allow the employee to appeal against any formal decision.

Every step below flows from those six principles. If you're ever unsure whether an action is defensible, ask which of the six it supports.

Before you start: informal action first

The Code is clear that many issues can and should be dealt with informally. A quiet conversation, a note-to-file, or a short coaching session often resolves things without triggering the formal machinery. Skipping this stage and jumping straight to a written warning for a first minor issue is one of the most common mistakes I see in SMBs, and it's usually because the manager has been putting off the conversation for weeks and now wants to "do it properly".

Informal action isn't a fudge. It's a legitimate stage. Just be clear with the employee that it is informal, keep a brief note of what was discussed, and make sure they understand what needs to change. If the same issue recurs, you can then move to the formal process with a clean paper trail.

Step 1: Establish the facts through investigation

Investigation is not the disciplinary. It's the separate fact-finding exercise that tells you whether there's a case to answer. In smaller businesses the same person often does both, and while that's not automatically unfair, it's better practice to separate the two where you have the resource. The investigator gathers evidence. The disciplinary manager decides on it.

Depending on the allegation, investigation might involve:

• Reviewing documentation (emails, timesheets, attendance records, CCTV where lawfully obtained).
• Interviewing witnesses and taking signed statements.
• Reviewing the employee's file, including previous warnings and their expiry dates.
• Meeting the employee themselves for an investigation interview (which is different from a disciplinary hearing).

An investigation meeting is not the point at which you decide anything. The employee doesn't have a statutory right to be accompanied at an investigation meeting, though many policies grant one anyway. What you cannot do is turn the investigation meeting into a de facto disciplinary by asking the employee to explain themselves and then issuing a warning at the end.

Suspension

Suspension is not a punishment. It's a neutral step used where the alleged conduct is serious enough that keeping the employee at work risks the investigation, other staff, or the business. It should be as short as possible, on full pay, and reviewed regularly. The ACAS guidance is explicit that suspension shouldn't be a knee-jerk response, and case law (notably Agoreyo v London Borough of Lambeth) has confirmed that unnecessary suspension can amount to a breach of the implied term of trust and confidence.

Step 2: Notify the employee in writing

Once the investigation has established there is a case to answer, you write to the employee. This letter has to do several specific things, and getting it wrong at this stage undermines everything after it:

• Set out the alleged misconduct or performance issue in sufficient detail that the employee can prepare a response. Vague allegations like "concerns about your conduct" are not enough.
• Enclose copies of any evidence you'll rely on, including witness statements, documents, and investigation notes.
• Confirm the date, time, and location of the hearing, giving reasonable notice (usually at least 3-5 working days).
• Explain the employee's right to be accompanied by a colleague or trade union representative under section 10 of the Employment Relations Act 1999.
• Set out the possible outcomes, including dismissal if that is a realistic possibility.

That last point matters. If the letter doesn't warn the employee that dismissal is on the table, you cannot then dismiss them at the end of the hearing. This trips up small employers regularly.

Step 3: Hold the disciplinary hearing

The hearing should be conducted by someone who has not been involved in the investigation, where practical. In an SMB with only one or two managers, that isn't always possible, but flagging the constraint in your notes and being scrupulous about fairness helps.

Run the meeting in a structured way:

1. Introduce everyone present and confirm the purpose.
2. Set out the allegations and the evidence.
3. Give the employee a full opportunity to respond, ask questions, present their own evidence, and call witnesses.
4. Adjourn to consider the response before deciding anything. Never announce an outcome on the spot.
5. Confirm the decision in writing within a reasonable period, usually within a week.

The right to be accompanied is a statutory one. If the employee's chosen companion isn't available on the proposed date, they can propose an alternative time within five working days of the original date, and you must accommodate it if reasonable.

Step 4: Decide the outcome

The Code doesn't prescribe a sanction ladder, but most policies use something like the table below. What matters is that the sanction is proportionate to the offence and consistent with how similar cases have been handled in the past.

Whatever the outcome, the written decision must explain what the sanction is, why it was chosen, what improvement is expected, how long the warning stays live, and how to appeal. A one-line letter saying "you are hereby given a final written warning" will not survive scrutiny.

Step 5: The appeal

Every formal disciplinary decision must carry the right of appeal. The appeal should be heard, where possible, by someone more senior than the person who made the original decision and who has not been previously involved. In small businesses this is often the hardest part of the Code to comply with. If the owner made the original decision, there's no one senior. In that case, an external HR consultant or a fellow director can hear the appeal, and tribunals accept this as a reasonable adjustment for size.

Appeals should be dealt with promptly. The employee sets out their grounds in writing, and the appeal manager can either review the original decision or re-hear the case entirely. The outcome, confirmed in writing, is final within the internal procedure.

Timelines and record keeping

The Code doesn't set rigid timelines, but delay is one of the top reasons tribunals reduce awards or find unfair dismissal. Here's a realistic timeline for a straightforward conduct case:

Keep contemporaneous notes of every meeting, signed by attendees where possible. Store copies of every letter, statement, and piece of evidence. Under Article 5(1)(e) of UK GDPR, hold personal data no longer than necessary, but for disciplinary matters that's usually the life of the warning plus a reasonable period for potential tribunal claims (a claim must normally be brought within three months less one day of the effective date of termination).

Common pitfalls that cost employers at tribunal

After years of advising SMBs, the same handful of mistakes come up again and again:

• Predetermined outcomes. Emails between managers before the hearing saying "we need to get rid of him" will surface in disclosure and destroy the employer's case.
• Investigator and dismissing manager being the same person. Not fatal, but adds risk. Separate the roles where you can.
• Refusing a companion who is inconvenient. The statutory right is broad. You can only refuse if the companion isn't a colleague or a certified union rep.
• Holding hearings while the employee is signed off sick without any adjustment. Consider written submissions, a home visit, or postponement. Occupational health advice helps.
• Inconsistent treatment. If a manager was given a final warning for the same conduct last year and this employee is dismissed, you need a genuine reason for the difference.
• Failing to consider mitigating circumstances. Length of service, previous clean record, personal circumstances, and any disability under the Equality Act 2010 all matter.
• Not giving live warnings any weight. The tribunal expects you to consider the totality of the record, but expired warnings should generally not be relied on.

Where absence and attendance cases fit in

Absence management sits awkwardly between conduct and capability. Persistent short-term absence, especially with a suspicious pattern around weekends or leave requests, is usually handled under a separate attendance policy, but the ACAS Code principles still apply: investigate, notify, hold a hearing, allow appeal.

Long-term sickness absence is usually a capability issue rather than conduct, and requires medical evidence, consideration of reasonable adjustments under the Equality Act 2010, and a genuine assessment of whether the employee can return to work in a reasonable timescale. Skipping straight to disciplinary action for someone on long-term sick is one of the fastest routes to a successful discrimination claim.

For a fuller treatment of how to structure absence policies, see our guides on sick leave policy in the UK and the Bradford Factor.

How Leavely helps

Disciplinary cases live or die on the quality of the record. When a manager claims an employee has been late 14 times in the last quarter, or absent on 9 separate occasions in a rolling 12-month window, the tribunal will want to see the underlying data. Reconstructing that from memory or a spreadsheet after the fact is where cases fall apart.

Leavely gives you a permanent, exportable record of every absence, holiday request, and attendance event. When you need to build a case, you can pull a single employee's absence history in seconds, filter by type, and export it as evidence for an investigation pack. Managers can annotate return-to-work interviews, so the paper trail is there before you need it, not scrambled together the week before a hearing. Leavely doesn't make the disciplinary decision for you, but it removes the "where's the evidence?" problem that so often derails otherwise fair cases.

Standard is £8 per active user per month for the core toolkit, and Ultra is £10 per active user per month with manager-approved shift cover added. Billing is self-serve and monthly, and the 14-day trial doesn't need a credit card.

Frequently asked questions

Does the ACAS Code apply to employees with under two years' service?

Yes. The Code applies to all disciplinary and grievance matters regardless of length of service. What changes at two years is the employee's right to claim ordinary unfair dismissal under section 108 of the Employment Rights Act 1996. Even without that right, employees can still claim automatic unfair dismissal (for whistleblowing or asserting a statutory right, for example) or discrimination, both of which have no qualifying period.

Can we dismiss on the spot for gross misconduct without following the full procedure?

No. Summary dismissal means dismissal without notice, not dismissal without process. You still need to investigate, put the allegations to the employee in writing, hold a hearing, and allow an appeal. Cutting corners on process for gross misconduct is one of the most common reasons those dismissals are found unfair.

What happens if the employee resigns during the disciplinary process?

You have a choice. You can accept the resignation and close the file, or you can continue the process to a conclusion. Most employers accept and close, but if the misconduct is serious (fraud, safeguarding, regulatory) you may want to conclude to establish the outcome for the record and any external reporting obligations. Resignation does not automatically prevent a constructive dismissal claim if the employee argues the procedure itself was a breach of contract.

How long should a written warning stay on file?

The Code doesn't prescribe a period, but common practice is 6 months for a first written warning and 12 months for a final written warning. Whatever you use, set it out in your disciplinary policy and apply it consistently. Once expired, warnings should generally be disregarded when considering future action.

Can we hear a disciplinary and grievance at the same time?

Sometimes. If an employee raises a grievance during a disciplinary process, particularly one that relates to the disciplinary itself, the ACAS guidance suggests you may temporarily suspend the disciplinary to deal with the grievance, or run the two concurrently if they are closely linked. The wrong answer is to ignore the grievance and press on regardless.

Does the 25% uplift apply to every unfair dismissal award?

No. The uplift under section 207A of the Trade Union and Labour Relations (Consolidation) Act 1992 applies only where a tribunal finds the employer unreasonably failed to comply with the ACAS Code, and the tribunal has discretion up to 25%. It can also apply the same uplift in reverse if the employee unreasonably failed to comply. The uplift attaches to most jurisdictions where the Code is relevant, including unfair dismissal, unlawful deductions, and discrimination compensation.