ACAS Early Conciliation: How It Works, Step by Step

What is ACAS Early Conciliation?

Before you can take a claim to an employment tribunal, you are legally required to go through ACAS Early Conciliation - a free, confidential service designed to see if your dispute can be resolved without a formal hearing.

ACAS (the Advisory, Conciliation and Arbitration Service) is an independent body. Early Conciliation is mandatory under section 18A of the Employment Tribunals Act 1996 and the certificate it produces is what unlocks your right to file an ET1 claim form.

Early Conciliation usually comes after you have tried to resolve the problem internally. For the full sequence of steps before a claim - from raising it informally through to this stage - see our guide on what to do before making a tribunal claim.

Step 1: Notify ACAS

Start by filling in the notification form on the ACAS website or calling 0300 123 1122. It is a short online wizard with five steps:

1. Choose whether to take part in early conciliation, or get a certificate straight away to go to tribunal. Both options use the same form.
2. Your details - full name, phone number, address.
3. Representative's details (optional) - only if a trade union rep, solicitor, friend or family member is acting for you. If you fill this in, ACAS will contact them instead of you.
4. Who the claim is against - the full legal name of your employer (use the proper form, for example "ABC Limited" rather than "ABC"). Getting this exactly right matters because a later mismatch between the certificate and your ET1 claim form can lead to the tribunal rejecting it.
5. Reasons for the dispute - a short, plain description of what happened. ACAS asks you to "tell us as much information as you can" so the conciliator can have a useful first conversation. Cover the main issue (for example, unfair dismissal, discrimination, unpaid wages), key dates (when the problem started, when you were dismissed, when you raised a grievance), and who was involved. Leave the legal argument and remedy figures for the ET1 itself.
6. Check and submit - review your answers and send.

Important: the moment you notify ACAS, the clock on your tribunal deadline pauses. Do not delay - contacting ACAS early gives you the maximum runway.

Step 2: ACAS contacts your employer

A conciliator reaches out to your employer to explain the process. The conciliator is neutral - they do not take sides, and they do not give legal advice. They check whether both parties want to try to resolve the dispute.

Your employer is not obliged to engage. Many do, because defending a tribunal claim is expensive and time-consuming even when the employer wins.

Step 3: Negotiation

If both sides are willing, the conciliator helps you explore what an agreement might look like. Typical outcomes include:

• A financial settlement
• An agreed reference
• An apology or acknowledgement
• Specific changes to the employer's practices

An agreement reached through ACAS is recorded on a COT3 form. The agreement can be binding as soon as you and your employer both accept the terms through the ACAS conciliator, even if that happens by phone or email and before the COT3 is written up or signed. Once it is binding, it is legally enforceable and you usually waive the right to bring tribunal claims about the matters covered. That makes the moment you say yes to the conciliator the point to be sure of the full scope, not only the moment you sign. See ACAS guidance on how conciliation works.

Step 4: The certificate

If conciliation does not result in a settlement, ACAS issues an Early Conciliation certificate with a unique reference number. You need that reference number to file your ET1 claim form.

The process can run for up to about 12 weeks for cases notified on or after 1 December 2025 (the older 6-week period applies to earlier notifications). There is no extension. It can end sooner: if either side does not want to continue, or the conciliator concludes a settlement is not possible, ACAS issues the certificate straight away, and when the period runs out the certificate is issued regardless. Provided you contacted ACAS before your time limit ran out, you have at least one month from receiving the certificate to submit your claim - if your time limit would otherwise end within that month, it is extended to one month after the certificate. Contacting ACAS after the time limit has already passed does not restart or extend it.

How Early Conciliation affects your tribunal deadline

Once you have the certificate, you have either:

• The remaining time left on your original deadline, or
• One month from the day you receive the certificate - whichever is longer

See our tribunal deadlines guide for worked examples and the rules on the trigger date.

Key things to know

• It is free - there is no charge for the service.
• It is confidential - discussions during conciliation cannot be used as evidence at tribunal.
• It pauses the clock - time spent in conciliation does not count toward your time limit (6 months less 1 day for events from 1 October 2026, 3 months less 1 day before).
• You can still go to tribunal - if no agreement is reached, you keep your right to file.
• You do not need a solicitor - many people go through Early Conciliation without legal representation. See our self-representation guide if you are weighing it up.

What happens after Early Conciliation?

If you settle, the COT3 is the end of the dispute (for the matters it covers). If you do not, the next step is your ET1 claim form. The certificate reference number is the link between the two.