Notification is compulsory

You cannot present a tribunal claim without first notifying Acas and obtaining an early conciliation certificate. Notification is compulsory; taking part in the conciliation itself is voluntary. Since 1 December 2025 the conciliation period can run for up to twelve weeks, increased from six.

Notify within your time limit

You must notify within your tribunal time limit. Notifying late does not revive an expired claim.

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Do not wait for a grievance, a disciplinary appeal, an internal investigation or ongoing settlement talks. None of them stops the clock.

How notification affects your deadline

Notifying pauses the countdown for the duration of conciliation, effectively extending your deadline. If agreement is not reached, you have at least one month from the date you receive the certificate to bring proceedings. In some cases you will have longer, because the balance of the original period is added back.

The extension of the window from six to twelve weeks gives considerably more room to negotiate — but only if you notified in time.

The arithmetic combining the pause, the one-month guarantee and the original limit is genuinely complicated, and getting it wrong is fatal. Have it calculated in writing.

How to notify

Online through the Acas early conciliation service, or by telephone. You provide your details, the employer’s correct legal name, and a short description of the dispute.

Get the legal entity right — not the trading name on the sign, but the registered company name on your contract, payslip or at Companies House. A certificate naming the wrong respondent creates problems later. You do not need to set out your full case at this stage.

What the conciliator does, and does not do

A conciliator is impartial. They will contact you, ask whether you want them to contact the employer, explain the process, pass offers and counter-offers, help explore terms, and record any agreement. Discussions are confidential and without prejudice.

They will not decide who is right, advise on the merits or value of your claim, represent your interests, or tell you whether an offer is good. That gap — between an impartial messenger and an adviser acting for you — is exactly where employees lose money.

What a COT3 is, and the warning attached

A settlement reached through Acas is recorded in a COT3. It is a legally binding conciliation agreement, and it is not the same as a settlement agreement.

Two differences matter enormously.

First, a COT3 does not require you to take independent legal advice for it to be valid. The statutory safety net that exists for settlement agreements — the six conditions, the named insured adviser, the confirmation that the conditions are met — does not apply. Nobody is required to explain what you are giving up.

Second, a COT3 can become binding once terms are agreed through the conciliator, before any document is signed. If you tell the conciliator you accept, you are usually committed. You cannot then change your mind, renegotiate, or add a term you forgot.

Take advice before you give the conciliator authority to settle. Not after the certificate arrives. Not after you have said yes.

A COT3 may cover payment, termination arrangements, notice and holiday, an agreed reference, confidentiality, non-disparagement, return of property, payment deadlines, and withdrawal of proceedings. Once agreed it is very difficult to reopen.

Note that the forthcoming section 202A restrictions on harassment and discrimination NDAs will apply to all types of agreement, including settlement agreements, employment contracts and COT3 agreements.

If no agreement is reached

Acas issues a certificate with a reference number, which you must enter on the ET1 claim form. Keep it safe. Receiving the certificate does not start proceedings — you must still submit the ET1 within the recalculated deadline.

Should you conciliate?

Almost always. It is free, confidential, pauses your deadline, and produces settlements in a very large proportion of cases without the cost, delay and exposure of a hearing. The question is not whether to conciliate, but whether you enter it with a properly evidenced valuation and a strategy, or hoping the conciliator will look after you. They cannot.