Before you can bring almost any claim to an employment tribunal, you must notify ACAS. That step is called Early Conciliation, and it is a legal requirement, not a formality. A conciliator contacts you and your employer separately and tries to help you reach an agreement, so the dispute ends without a hearing. Taking part in the conciliation itself is voluntary — notifying ACAS is not. Get the timing wrong and you lose the right to claim at all, however strong your case is. This guide takes you through the process step by step, from your first notification to the certificate that unlocks the tribunal.
Contents
- What Early Conciliation is
- When you must notify ACAS
- Time limits and how the clock is paused
- Step by step: how the process works
- What ACAS will and will not do
- COT3 settlement agreements
- Deciding whether to settle
- When conciliation ends without agreement
- Exceptions to Early Conciliation
- FAQs
- How the National Employees Union can help
What Early Conciliation is
Early Conciliation is a free, confidential service run by ACAS under Section 18A of the Employment Tribunals Act 1996. Its purpose is narrow: to give you and your employer a chance to settle a workplace dispute before it becomes a tribunal claim.
A conciliator speaks to each side separately, usually by telephone. They pass offers and positions between you, test how realistic each side is being, and record any agreement reached. They do not hold a hearing, take evidence or decide who is right.
That neutrality is the point. The conciliator has no stake in the outcome, which is why employers often engage more openly than they did during your internal grievance or disciplinary process.
When you must notify ACAS
You must notify ACAS before you make a claim to an employment tribunal. This applies to nearly all claims, including unfair dismissal, constructive dismissal, discrimination, unlawful deduction from wages, holiday pay and redundancy pay and consultation failures.
You should not notify ACAS as your first move. A tribunal expects you to have tried to resolve the problem internally — informally, then through a grievance, then through an appeal. If you skip those stages, a judge can reduce your compensation by up to 25% under the ACAS Code of Practice on disciplinary and grievance procedures.
Internal steps do not stop the clock. However long your grievance or appeal takes, you must still notify ACAS inside your tribunal time limit.
Time limits and how the clock is paused
For most claims, the time limit is three months minus one day from the date of the act you are complaining about. For dismissal, that date is the effective date of termination — your last day of employment, not the day you were told.
Notifying ACAS pauses the clock, but only if you notify within the original time limit. The pause starts the day after you contact ACAS (Day A) and ends on the day you receive your certificate (Day B). Your deadline is extended by the length of that period, and you always get at least one month after Day B to submit your claim.
| Stage | What happens |
|---|---|
| Day 0 | The act you are complaining about, or your effective date of termination |
| Day A | The day you notify ACAS — the clock pauses from the following day |
| Day A to Day B | Early Conciliation runs, for up to 12 weeks |
| Day B | You receive the Early Conciliation certificate — the clock restarts |
| Deadline | The original limit plus the paused days, or one month after Day B if that is later |
The conciliation period itself was extended from six weeks to 12 weeks by the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) (Amendment) Regulations 2025, for notifications made on or after 1 December 2025. Longer conciliation gives more room to settle, but it also means your dispute can stay unresolved for months.
One change is coming. Under the Employment Rights Act 2025, the time limit for most tribunal claims rises from three months to six months for acts occurring on or after 1 October 2026. If your issue arose before that date, the three-month limit still applies to you. Never rely on the extension without checking which regime covers your dates.
Step by step: how the process works
Step 1: Notify ACAS
Complete the Early Conciliation notification form on the ACAS website, or telephone ACAS. You give your details, your employer’s details and a short description of the dispute. You do not have to set out your case or your evidence at this stage.
Name every employer or individual you may want to claim against. You need a separate certificate number for each respondent, and a missing name at this stage can block that part of your claim later.
Step 2: The conciliator makes contact
An ACAS conciliator calls you to explain the process and ask what outcome you are looking for. They then contact your employer to ask whether they want to take part.
If your employer declines, conciliation ends and ACAS issues your certificate. That is not a defeat. It simply moves you to the tribunal stage sooner.
Step 3: Positions are exchanged
The conciliator carries offers and responses between the two sides. Nothing you say is passed on without your agreement, and nothing said in conciliation can be used as evidence at a tribunal.
Use this stage to be specific. “Compensation” is not a position; a figure, a reference and an agreed leaving date is a position.
Step 4: Agreement or certificate
If you reach agreement, the conciliator records it in a COT3. If you do not, ACAS issues an Early Conciliation certificate with a unique reference number. You need that number to submit an ET1 claim form, and the employment tribunal process cannot begin without it.
What ACAS will and will not do
Understanding the conciliator’s limits saves you from relying on help that will not come.
| ACAS will | ACAS will not |
|---|---|
| Explain the process and the options | Represent you or take your side |
| Pass offers between you and your employer | Tell you whether your claim is strong |
| Record any settlement in a binding COT3 | Give you legal advice |
| Issue your certificate promptly if talks fail | Prepare your case for the tribunal |
This is where representation matters. The conciliator cannot value your claim, so you need your own assessment of what it is worth before you name a figure. the National Employees Union’s legally trained reps do that work with you, and can conciliate on your behalf.
COT3 settlement agreements
A COT3 is the agreement that records a settlement reached through ACAS. Once both sides agree the wording, it is legally binding and it ends the claims it covers for good.
A COT3 is not the same as a settlement agreement offered directly by your employer. A settlement agreement requires independent legal advice from a named adviser before it is valid. A COT3 does not, because the conciliator’s involvement replaces that safeguard. That makes a COT3 quicker to complete — and easier to sign before you have thought it through.
Check the wording carefully. A COT3 will usually cover the payment amount and date, the tax treatment, a reference, confidentiality, and the list of claims you are giving up. Wide wording can waive claims you have not yet identified, including personal injury or pension claims.
Deciding whether to settle
Settlement buys certainty. A tribunal claim can take a year or more to reach a hearing, and no outcome is guaranteed. Against that, the sum on the table is often lower than a full award.
Weigh four things: the strength of your evidence, the value of the claim, the time you are prepared to spend, and what you actually want. If you want your job back or a change in your employer’s behaviour, money alone will not deliver it.
Remember that qualifying service still shapes the picture. For dismissals with an effective date of termination before 1 January 2027, you generally need two years’ service to bring an ordinary unfair dismissal claim. From that date, the Employment Rights Act 2025 reduces the qualifying period to six months and removes the cap on the compensatory award. Discrimination and automatically unfair dismissal claims need no qualifying service at all.
When conciliation ends without agreement
If no agreement is reached, or your employer will not take part, ACAS issues your certificate by email. Read it immediately and note the date you received it, because that date sets your deadline.
You then submit your ET1 claim form to the tribunal, quoting the certificate number exactly as written. A wrong or missing number causes rejection, and a rejected claim can easily be resubmitted too late.
Conciliation does not stop there. ACAS can still help you settle at any point after the claim is issued, right up to the hearing itself, and many claims settle on that basis.
Exceptions to Early Conciliation
A small number of situations do not require you to notify ACAS. You are exempt if another person has already been through Early Conciliation for the same dispute and you are claiming with them, if your employer has already contacted ACAS about the dispute, or if you are applying for interim relief within seven days of dismissal.
Exemptions are narrow and easy to misjudge. If you are not certain one applies to you, notify ACAS anyway — doing so costs you nothing and protects your claim.
FAQs
Is ACAS Early Conciliation compulsory?
Notifying ACAS is compulsory before most tribunal claims. Taking part in the conciliation itself is voluntary, and either side can decline. If you do not notify ACAS, the tribunal will reject your claim.
How long does Early Conciliation last?
Up to 12 weeks for notifications made on or after 1 December 2025, extended from the previous six weeks. It can end sooner if either side withdraws or an agreement is reached. ACAS issues your certificate as soon as it ends.
Does contacting ACAS extend my time limit?
Yes, provided you notify within the original limit. The clock pauses from the day after you contact ACAS until the day you receive the certificate, and you always have at least one month after that date to claim.
Do I have to accept what ACAS proposes?
No. The conciliator has no power to impose an outcome and cannot pressure you into agreeing. You can reject any offer and take your claim to the tribunal instead.
Is a COT3 binding?
Yes. Once agreed, a COT3 is legally binding and prevents you bringing the claims it covers. Take advice on the wording before you agree it, because it cannot be reopened afterwards.
Can I still claim if conciliation fails?
Yes. Failure to settle is the normal route to a hearing, not a mark against you. Use the certificate number on your ET1 and submit it before your deadline.
How the National Employees Union can help
Early Conciliation looks simple and is not. The conciliator cannot value your claim or advise you, so the quality of your outcome depends on the preparation you bring to the call.
National Employees Union members get help calculating what the claim is worth, a rep to conciliate on their behalf, a full review of any COT3 wording before it is agreed, and support with the ET1 if conciliation ends without agreement. Our reps are legally trained and deal with ACAS every week.
Time limits are strict and missing one ends the claim. Join the National Employees Union today — membership from £15/month — or contact us to discuss your situation.
Written by the National Employees Union team. We support members through conciliation and tribunal claims across the UK. This guide is reviewed regularly and was last updated in August 2026.
