Before you can go to tribunal, you must contact ACAS first.

Early conciliation is mandatory — and it affects your 3-month deadline. Here is exactly what it involves, how long it takes, and what happens if your employer will not engage.

Is ACAS early conciliation compulsory?

Yes — with very limited exceptions. Before you can submit an ET1 claim form to the Employment Tribunal, you must contact ACAS and receive an early conciliation certificate. If you skip this step, your claim will be rejected. Exceptions include claims involving national security, certain interim relief applications, and some multiple claimant situations.

How long does ACAS early conciliation take?

The standard conciliation period is up to 6 weeks. ACAS can extend this by a further 2 weeks if both parties agree and settlement looks achievable. If conciliation fails (or you or your employer choose not to engage), ACAS issues an early conciliation certificate and you can then proceed to the tribunal.

Does contacting ACAS stop the 3-month clock?

Yes — this is one of the most important effects. The 3-month time limit for most Employment Tribunal claims is frozen (tolled) from the day you contact ACAS until the day ACAS issues your certificate. This means you get extra time to file your ET1 on top of the original 3-month period. The calculation can be complex — Start My Claim tracks this automatically.

Do I have to accept a settlement through ACAS?

No. Participation in conciliation is entirely voluntary and you can withdraw at any time. If ACAS cannot help you reach a settlement, they issue an early conciliation certificate and you proceed to the tribunal. Anything discussed during conciliation is confidential and cannot be used as evidence at tribunal.

What information do I need to provide to ACAS?

Basic details: your name and address, your employer's name and address, and a brief description of your complaint. You do not need to provide detailed evidence at this stage — the full facts come in your ET1 later. ACAS will assign a conciliator who contacts both sides.

Can I contact ACAS online?

Yes. You can submit the ACAS early conciliation notification form online at acas.org.uk, or call the ACAS helpline on 0300 123 1100. Online is usually faster and creates a clear timestamp for when the conciliation period started — which matters for your time limit calculation.

What happens if my employer refuses to engage with ACAS?

ACAS cannot force your employer to participate. If your employer declines or does not respond, ACAS will issue your early conciliation certificate quickly (often within a couple of days) and you can proceed to file your ET1. The tribunal will not penalise you for an employer's refusal to engage.

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ACAS Early Conciliation

Before you can go to tribunal,

you must contact ACAS first.

Before ANY tribunal claim

Conciliation period (+ 2 weeks if agreed)

3-month deadline paused while ACAS is active

What is ACAS early conciliation?

ACAS (Advisory, Conciliation and Arbitration Service) is an independent body set up to resolve workplace disputes without them needing to go to a full tribunal hearing. Early conciliation is a free, impartial service where an ACAS conciliator tries to help you and your employer reach a mutually agreed settlement.

Since 2014, contacting ACAS has been a legal prerequisite before submitting most Employment Tribunal claims.

The tribunal will reject your ET1 if you have not received an ACAS early conciliation certificate — even if the certificate confirms that conciliation was unsuccessful.

Key point: conciliation is confidential

Everything discussed with your ACAS conciliator is without prejudice — it cannot be used as evidence at the tribunal. This means you can negotiate freely without any admission being used against you later.

How the process works

From first contact to certificate — step by step.

Complete the online early conciliation notification form at acas.org.uk or call 0300 123 1100. Provide your name, your employer's details, and a brief description of your claim. This takes about 10-15 minutes.

This is when your 3-month clock freezes.

ACAS contacts both parties

An ACAS conciliator is assigned and contacts you and your employer separately. They will not share privileged information from either side without permission.

Conciliation discussions

The conciliator facilitates discussions — by phone, not in person. There are no formal hearings. You can be represented by a solicitor, trade union rep, or friend, or act entirely on your own.

Settlement or certificate

If you reach a settlement, it is recorded on a COT3 form — a legally binding agreement. If no settlement is reached (or either party withdraws), ACAS issues an early conciliation certificate with a unique reference number.

With your ACAS certificate number, you can submit your ET1 claim via MyHMCTS. Start My Claim calculates your deadlines automatically and compiles your ET1 section by section.

You now have a fresh window to file based on when ACAS issued the certificate.

How ACAS affects your 3-month deadline

The time limit calculation is more complex than most people realise.

You have 3 months minus one day from the date of dismissal (or the date the last act you are complaining about occurred) to start ACAS early conciliation.

Miss this and your claim will usually be rejected.

What ACAS does to the clock:

Day A = the day you contact ACAS. Day B = the day ACAS issues your certificate. The period from A to B is added on top of your original deadline, plus one month.

Dismissed 1 January. Original deadline: 31 March. Contact ACAS 20 March. ACAS certificate issued 10 April (21 days later). New filing deadline: 31 March + 21 days + 1 month = approximately 1 June.

These calculations are complex and fact-specific. Start My Claim tracks your exact deadlines automatically.

What to expect from your conciliator

ACAS early conciliation — common questions

Employment tribunal time limit

Know your 3-month deadline and tolling.

Complete guide to the tribunal claim form.

Represent yourself at tribunal

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Start My Claim is not a law firm. Content is for informational purposes only and does not constitute legal advice.