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

Last updated: March 2026

Quick Answer

Since April 2014, claimants must notify ACAS before presenting an employment tribunal claim. The early conciliation (EC) process pauses the limitation clock under s.207B of the Employment Rights Act 1996, applying whichever of two extension methods gives the later deadline. Each respondent requires a separate notification and certificate. The tribunal will reject any ET1 without a valid ACAS certificate number unless an exemption applies.

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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 one calendar month to attempt conciliation. This period may be extended by a further 14 days with both parties' consent. 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 — but the extension operates through two different methods, and you must apply whichever gives the later deadline.

Method A (s.207B(3))

If the normal time limit would expire during the conciliation period, the deadline is extended to Day B plus one day.

Method B (s.207B(4))

If the normal time limit has not yet expired when the EC certificate is issued, the period between Day A and Day B is added to the remaining time.

Worked Example

Method A: Normal limit (31 March) does not expire during EC period (15 Feb–15 Mar), so Method A does not apply.

Method B: Day B minus Day A = 28 days. Normal limit (31 March) plus 28 days = 28 April. Extended deadline is 28 April.

Practitioner tip: Always calculate both methods and apply whichever gives the later expiry date. 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 — using only one method instead of applying the later of Method A and Method B
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.