ACAS Early Conciliation: A Practitioner's Guide to Time Limits and Strategy

1. The Mandatory Requirement

Since 6 April 2014, a prospective claimant must notify ACAS before presenting an ET1 claim form (Employment Tribunals Act 1996, s.18A). The tribunal will reject any claim that does not include an ACAS EC certificate number unless an exemption applies (Rule 12 of the Employment Tribunal Procedure Rules 2024).

This is not optional. It is not a formality. Failure to comply is one of the most common — and most avoidable — reasons for claims being rejected at the door.

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2. How to Notify ACAS

• Online: www.acas.org.uk/early-conciliation (available 24/7)
• Telephone: 0300 123 1100 (Monday to Friday, 8am–6pm)

You will need:

• The prospective claimant's name, address, and contact details
• The prospective respondent's name and address
• A brief description of the dispute

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3. The Conciliation Period

Once notification is made, ACAS has up to 12 weeks to try to promote a settlement (rule 6(1) of the Early Conciliation Rules, for notifications made on or after 1 December 2025; it was 6 weeks before that). The key dates are known as Day A (notification date) and Day B (certificate date).

ACAS will issue an EC certificate when:

• A settlement (COT3) is reached
• The conciliation period expires without settlement
• ACAS determines that conciliation is not appropriate or not possible
• The prospective claimant asks ACAS to stop conciliating

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4. Time Limit Extension (s.207B ERA 1996)

This is the section that catches people out. The period between Day A and Day B does not count towards the limitation period — and the extension works in two steps applied in order: first s.207B(3), then s.207B(4).

Step 1 (s.207B(3))

The days from the day after Day A up to and including Day B are not counted. Add that number of days to the normal limit.

Step 2 (s.207B(4))

If the limit (after step 1) would expire between Day A and one month after Day B, it expires instead one month after Day B.

Worked Example

Step 1: 28 days (16 February to 15 March) are not counted, so the limit moves to 28 April 2026.

Step 2: One month after Day B is 15 April 2026. 28 April falls after that, so step 2 does not change it. Extended deadline: 28 April 2026.

Second example (EDT on or after 1 October 2026): EDT 1 November 2026, so the normal limit is 30 April 2027 (6 months less 1 day). Day A is 10 April 2027 and Day B is 20 April 2027. Step 1 adds 10 days, giving 10 May 2027. That falls between Day A and one month after Day B (20 May 2027), so step 2 applies and the deadline becomes 20 May 2027.

Practitioner tip: Always apply step 1 and then check step 2. Keep a careful written record of Day A, Day B, the original limitation date, and the extended deadline. Errors here are costly and common.

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5. Exemptions from ACAS EC

EC is not required where:

• Another person making the same claim has already obtained an ACAS EC certificate for that respondent
• ACAS does not have the power to conciliate on the claim
• The employer has already been in touch with ACAS
• The claim is solely for unfair dismissal and includes an application for interim relief (s.128 ERA 1996) — this exemption is narrow

If you rely on an exemption, you must select it on the ET1. If the tribunal disagrees that the exemption applies, the claim will be rejected.

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6. Multiple Respondents

A separate ACAS EC notification must be made against each respondent. A single certificate does not cover multiple respondents. This is one of the most common grounds for rejection of the ET1, particularly in discrimination claims where individuals are named alongside the employer.

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7. Strategic Considerations

1. Timing — notify ACAS early to preserve as much extension time as possible. Do not wait until the last week of the limitation period. If you notify ACAS with only days to spare, the extension may still not save you if there is a postal delay or administrative error.

2. Confidentiality — communications during EC are confidential and cannot be used in tribunal proceedings without both parties' consent. This is a genuine safe space for settlement discussions.

3. COT3 settlements — a settlement reached through ACAS (known as a COT3) is binding and enforceable. Unlike a private settlement agreement, it does not require independent legal advice. The terms are recorded by the ACAS conciliator and both parties are bound.

4. Name matching — the name on the ACAS certificate must match the claimant and respondent names on the ET1. Discrepancies — even minor ones — may result in rejection. Ensure consistency at the notification stage and double-check before filing.

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Common Mistakes to Avoid

1. Notifying ACAS too late — leaving insufficient time for the extension to prevent expiry
2. Failing to obtain individual certificates for each respondent
3. Name discrepancies between the ACAS certificate and the ET1
4. Miscalculating the extension — forgetting to apply s.207B(3) first and then check s.207B(4)
5. Assuming EC is not required when the exemption does not actually apply

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How BundleCreator Helps

Once ACAS conciliation concludes and your claim proceeds to a hearing, you will need to prepare a tribunal bundle. The ACAS EC certificate itself should be one of the first documents in the bundle. BundleCreator's employment tribunal templates include all the practitioner documents you need — automatically paginated and indexed to tribunal standards.

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Related Articles

• ET1 Claim Form: Complete Guide
• ET3 Response Form: Defending a Claim
• Employment Tribunal Time Limits
• Employment Tribunal Bundle Guide

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This article provides general information about employment tribunal procedures in England and Wales. It is not legal advice, and BundleCreator.co is not a law firm and does not provide legal services. Before submitting any documents to the Employment Tribunal, you should seek guidance from a qualified legal representative such as a solicitor, barrister, or trade union representative. Free initial advice may also be available from Citizens Advice, ACAS, or your local Law Centre.