Time limit: Most employment tribunal claims must be started within 3 months minus 1 day of the act you're complaining about. Contacting ACAS stops this clock — do it as soon as possible, even if you haven't decided whether to claim.
What is ACAS early conciliation?
ACAS (Advisory, Conciliation and Arbitration Service) is an independent public body that helps resolve workplace disputes. Before an employee can submit a claim to the employment tribunal, they must first notify ACAS and go through a process called early conciliation. This became mandatory in May 2014.
The purpose is to give both sides an opportunity to settle the dispute without the cost and stress of tribunal proceedings. It is free, voluntary in spirit (you cannot be forced to settle), and confidential.
How does it work?
- You notify ACAS — By phone (0300 123 1100) or online at acas.org.uk. You provide basic details: your name, employer's name, and the type of dispute.
- ACAS contacts you — A conciliator calls you to understand your situation and explain the process.
- ACAS contacts your employer — The conciliator approaches your employer to see if they are willing to discuss settlement.
- Shuttle conciliation — The conciliator acts as a go-between, relaying offers and responses between the parties. They do not take sides or give legal advice, but can help both parties understand a realistic range of outcomes.
- Either a settlement is reached, or not — If settlement is agreed, it is recorded in a COT3 agreement (see below). If not, ACAS issues an Early Conciliation Certificate allowing you to proceed to tribunal.
How long does early conciliation take?
The early conciliation period lasts up to 6 weeks (with a possible extension of up to 2 more weeks by mutual agreement). During this period, the tribunal time limit is paused. Once the certificate is issued (either because conciliation ended or 6 weeks elapsed), the clock restarts — and you typically have one calendar month from the certificate date to submit your ET1.
Does ACAS conciliation stop the tribunal clock?
Yes — this is crucial. When you notify ACAS, Day A (the start of conciliation) is recorded. If you receive your certificate on Day B, the tribunal time limit is extended by the number of days between Day A and Day B, plus an additional month. This means that even if you notify ACAS on the last day of the 3-month period, you will have additional time after conciliation ends.
Do I have to engage with early conciliation?
You must notify ACAS — but you are not required to actively engage in negotiations. If you or your employer do not wish to conciliate, ACAS will issue the certificate promptly, and you can proceed to tribunal. However, refusing to engage can sometimes be taken into account by a tribunal when considering costs.
What is a COT3 agreement?
If early conciliation results in a settlement, the terms are recorded in a COT3 agreement. A COT3 is legally binding and settles the claims covered by it — similar to a settlement agreement, but simpler. Unlike a settlement agreement, you do not need independent legal advice for a COT3 to be valid (though taking advice is strongly recommended). Once signed, you cannot pursue the covered claims at tribunal.
COT3 agreements are commonly used for straightforward disputes. For more complex cases involving multiple claims, multiple payments, or where confidentiality is important, a full settlement agreement (with solicitor involvement) is usually preferable.
ACAS during live tribunal proceedings
Even after tribunal proceedings have been issued, ACAS conciliators (known as "open period" conciliators) remain available to assist with settlement. Many cases settle at this stage — often just before the final hearing, when both parties have seen each other's witness statements and can assess the risks more clearly.
Estimate your case value
Before entering ACAS conciliation, use our Employment Tribunal Calculator to understand what your claim could be worth. This will help you assess whether any settlement offer is reasonable.