ACAS Early Conciliation Certificate Guide: Everything You Need Before You File

ACAS Early Conciliation Certificate Guide: Everything You Need Before You File

Before you can submit an Employment Tribunal claim, you must contact ACAS. This is not optional. The law requires it. If you skip this step, your claim will be rejected at the door — no matter how strong your case is. This guide explains exactly what ACAS Early Conciliation is, what the 12-week process involves, how your deadlines are affected, and what you need to do to protect your right to bring a claim in 2026.

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When Do You Need ACAS Early Conciliation?

You must notify ACAS before you submit an ET1 form to the Employment Tribunal. This obligation applies to almost every employment tribunal claim, including unfair dismissal, wrongful dismissal, discrimination, unlawful deduction of wages, whistleblowing detriment, and constructive dismissal.

There are only a small number of exceptions — for example, certain applications involving interim relief, or situations where your employer is already in collective conciliation. In the vast majority of cases, however, early conciliation is a mandatory gateway. You cannot proceed to tribunal without it.

The moment you decide you may wish to bring a claim, you should contact ACAS promptly. The reason is simple: your limitation period is ticking, and the rules around how early conciliation affects your time limit are detailed and easy to misapply.

What ACAS Early Conciliation Is

ACAS — the Advisory, Conciliation and Arbitration Service — is an independent public body funded by the government. Its role in early conciliation is to act as a neutral go-between, facilitating settlement discussions between you and your employer before any formal tribunal claim is filed.

Early conciliation is not a court process. There is no judge, no formal hearing, and no binding ruling. It is a voluntary negotiation assisted by a trained ACAS conciliator. The conciliator does not represent either party. They will speak separately to you and to your employer, relay offers and responses, and help both sides explore whether a settlement is achievable.

If agreement is reached, the outcome is typically a COT3 agreement — a legally binding settlement that ends the dispute in exchange for agreed terms, which usually include a payment and/or agreed references. Once signed, you cannot bring a tribunal claim on the same matter.

If no agreement is reached, ACAS will issue an Early Conciliation Certificate. This certificate is your proof that you have completed the mandatory step. You will need the certificate number when you fill in your ET1.

From December 2025, the maximum early conciliation period has been set at 12 weeks. This is the outer limit during which ACAS can keep the conciliation window open. In practice, many cases conclude sooner — either because settlement is reached or because both parties (or one party) decide conciliation will not be productive.

How to Start ACAS Early Conciliation: Step by Step

Step 1 — Contact ACAS to Notify Your Claim

You begin by submitting a notification to ACAS online at acas.org.uk or by telephone. The online route is generally faster. You will be asked for:

• Your name, address, and contact details
• Your employer’s name and address
• A brief description of the type of dispute (for example, unfair dismissal or discrimination)

You do not need to set out your full legal case at this point. This initial notification is not your tribunal claim. It simply triggers the early conciliation process and — critically — stops the clock on your limitation period from the date ACAS receives it.

Step 2 — ACAS Contacts Your Employer

Once your notification is received, ACAS will contact your employer to ask whether they are willing to engage in early conciliation. Your employer is not legally required to participate. If they refuse, or fail to respond, ACAS will issue the Early Conciliation Certificate promptly and you may proceed to tribunal.

Step 3 — The Conciliation Period Begins

If your employer agrees to engage, ACAS will assign a conciliator to your case. The conciliator will speak with you and with your employer — usually by telephone — to understand each party’s position and explore the scope for settlement.

You are under no obligation to accept any offer. You retain full control throughout. The conciliator cannot compel either side to agree to anything. Everything discussed during early conciliation is confidential and without prejudice — meaning it cannot generally be used against you in tribunal proceedings.

The 12-week maximum period from December 2025 means ACAS can extend the conciliation window up to that point if both parties consent and there is genuine progress being made. Previously, the maximum was one month (with an optional extension). The extended 12-week period gives both sides more time to reach a resolution before the formality and cost of tribunal proceedings commence.

Step 4 — Settlement or Certificate

There are two ways the process ends:

If settlement is reached: You and your employer sign a COT3 agreement through ACAS. The conciliator will draft the agreement based on the terms both sides have agreed. You should read this carefully before signing. Once signed, your tribunal rights on that claim are waived.

If settlement is not reached: ACAS issues an Early Conciliation Certificate. The certificate confirms the date ACAS received your notification (the Day A date) and the date the certificate was issued (the Day B date). Both dates are important for calculating your amended limitation period. Keep this certificate safe — you will need the EC certificate number when completing your ET1.

Step 5 — Submit Your ET1

Once you hold the certificate, you may submit your ET1 to the Employment Tribunal. You must do this within the amended time limit calculated from your Day A and Day B dates (see the Key Deadlines section below). You will enter the EC certificate number in the designated field on the ET1 form.

Key Deadlines

Employment tribunal claims are subject to strict time limits. Getting these wrong can end your case before it has begun.

The standard time limit for most employment claims is three months less one day from the act complained of — for example, the effective date of termination in an unfair dismissal claim, or the date of the discriminatory act in a discrimination claim.

How early conciliation affects your time limit is governed by a specific statutory calculation. When you notify ACAS, time stops running. It remains stopped until ACAS issues the Early Conciliation Certificate. Once the certificate is issued, time starts running again. However, a minimum extension of one calendar month is added to your original deadline.

In practical terms:

• If you notify ACAS with time to spare, your deadline will be paused and then extended by the duration of the conciliation period, plus a minimum one-month addition.
• If you notify ACAS after your original three-month deadline has already expired, the law will not revive an already-expired claim. Time limits are treated very strictly by tribunals.

The key rule: Do not wait until the last moment. Notify ACAS as early as possible. If you are unsure whether your time limit has passed, treat it as urgent and act immediately.

For whistleblowing and health and safety detriment claims, the same three months less one day rule applies from the date of the detriment. For unlawful deduction of wages, the limit runs from the last in a series of deductions, or from the single deduction complained of. For equal pay, limits differ and are longer.

If you are uncertain which time limit applies to your specific situation, do not guess. The tribunal has very limited discretion to extend time, and that discretion is rarely exercised in favour of claimants who simply missed the date.

What Happens After Conciliation?

If you reach a COT3 settlement, the matter is concluded. The agreement is binding and enforceable. You should retain a copy of the signed agreement for your records.

If conciliation does not result in settlement and you receive your Early Conciliation Certificate, you have the right to submit your ET1. Filing the ET1 opens the formal tribunal process. The Employment Tribunal will send a copy of your claim to the respondent (your employer), who will have 28 days to submit an ET3 response.

If your employer does not submit an ET3 in time, you may apply for a default judgment. If they do respond, the tribunal will consider whether the case should proceed to a preliminary hearing, a case management order, or straight to a final hearing on the merits.

Receipt of the certificate does not mean your claim is strong or will succeed. It means only that you have satisfied the mandatory procedural gateway. The substance of your claim will be tested at tribunal on evidence and law.

Common Mistakes

1. Missing the ACAS notification deadline. Many claimants assume the three-month clock stops automatically or that they have more time than they do. The clock only stops when ACAS receives your notification. Act early.

2. Treating early conciliation as informal or optional. It is a legal requirement. There are almost no exceptions. Attempting to file an ET1 without a valid EC certificate number will result in the claim being rejected.

3. Saying too much during conciliation. Everything you say to the conciliator is confidential and without prejudice, but that does not mean you should make rash concessions or exaggerate your position. Keep statements measured and factual.

4. Accepting a low offer without understanding your case value. Without proper preparation, claimants sometimes settle for far less than their claim is worth. Before entering conciliation, you should have a realistic sense of your likely tribunal award.

5. Failing to retain the EC certificate. The certificate number is required on your ET1. Losing or misplacing it causes avoidable delay. Keep it in a safe location — ACAS can reissue it, but this takes time.

6. Assuming ACAS will advise you. The conciliator is neutral. They will not advise you on whether to accept an offer, whether your case is strong, or what a tribunal might award. Their role is facilitation only.

A: You must notify ACAS before you can submit an ET1 — that notification is mandatory. However, participation in the conciliation itself is voluntary for both you and your employer. If either party declines to engage, ACAS will issue the Early Conciliation Certificate promptly so you can proceed to tribunal.

Q: What is the EC certificate number and where do I find it?
A: The Early Conciliation Certificate is issued by ACAS at the end of the conciliation process, whether or not settlement was reached. It contains a unique reference number (usually in the format ACAS/NE/XXXXXX/XX). You will need this number when you complete the ET1 form. ACAS sends the certificate by email and post. Keep it safe — if you lose it, contact ACAS to request a reissue.

Q: How does the 12-week early conciliation period affect my three-month time limit?
A: When ACAS receives your notification, the limitation clock pauses (this is known as Day A). It stays paused until the day ACAS issues the certificate (Day B). The period between Day A and Day B is then added back on to your original deadline, with a minimum extension of one calendar month. You then have the remainder of your adjusted deadline to file your ET1. The calculation can be complex — if in doubt, act promptly rather than waiting to understand the exact date.

Q: My employer refused to engage with ACAS conciliation. Does that affect my claim?
A: No. An employer’s refusal to engage with early conciliation does not affect the validity of your claim or prevent you from proceeding to tribunal. ACAS will issue the certificate quickly in those circumstances. You may however wish to consider whether that refusal is relevant context when your case is managed at tribunal.

Q: Can I contact ACAS again after the certificate is issued if I want to settle before the hearing?
A: Yes. ACAS conciliation services remain available throughout tribunal proceedings, right up to the hearing. If you and your employer wish to negotiate a settlement at any stage after the ET1 is filed, ACAS can assist again under what is known as conciliation during proceedings. This does not restart the early conciliation process — it is a separate, ongoing support available to both parties.

Related Court Forms & Guides

• Form N260: Statement of Costs — the costs schedule used at summary assessment.
• Form N244: Application Notice — the form for interim applications.
• Start a Money Claim Online (OCMC) — where most civil money claims begin.
• Particulars of Claim — setting out the basis of your claim.
• Civil Court Forms Index — every civil court form guide in one place.

Frequently asked questions

Do I have to use ACAS before bringing an Employment Tribunal claim?

Yes. You must notify ACAS before you can submit an ET1, and this notification is mandatory for almost every employment tribunal claim — including unfair dismissal, wrongful dismissal, discrimination, unlawful deduction of wages, whistleblowing detriment and constructive dismissal. Participation in the conciliation itself is voluntary; if either party declines to engage, ACAS issues the Early Conciliation Certificate promptly so you can proceed.

What is the EC certificate number and where do I find it?

The Early Conciliation Certificate is issued by ACAS at the end of the process, whether or not settlement was reached, and contains a unique reference number. You will need this number when you complete the ET1 form. ACAS sends the certificate by email and post — keep it safe, as losing it causes avoidable delay (ACAS can reissue, but it takes time).

How does early conciliation affect my three-month time limit?

When ACAS receives your notification the limitation clock pauses (the Day A date). It stays paused until the day ACAS issues the certificate (the Day B date), and that period is added back to your original deadline with a minimum extension of one calendar month. The calculation can be complex, so notify ACAS as early as possible rather than waiting to work out the exact date.

What happens if my employer refuses to engage with ACAS?

An employer’s refusal to engage does not affect the validity of your claim or prevent you from proceeding to tribunal. ACAS will issue the certificate quickly in those circumstances. You may, however, wish to consider whether that refusal is relevant context when your case is managed at tribunal.

What is a COT3 and what does it mean if I sign one?

If settlement is reached during conciliation, the outcome is typically a COT3 agreement — a legally binding settlement that ends the dispute in exchange for agreed terms, usually a payment and/or agreed references. Read it carefully before signing: once signed, you cannot bring a tribunal claim on the same matter.

Can I use ACAS again after the certificate is issued?

Yes. ACAS conciliation services remain available throughout tribunal proceedings, right up to the hearing. If you and your employer wish to negotiate a settlement at any stage after the ET1 is filed, ACAS can assist again under conciliation during proceedings — this is separate from early conciliation and does not restart it.

Related guides: Employment Tribunal Schedule of Loss · Particulars of Claim · Form N244: Application Notice · All civil court forms