Almost nobody goes straight to an employment tribunal. There's a compulsory step in front of it, and it quietly decides whether a lot of claims survive. It's called early conciliation, and ACAS runs it.
What early conciliation actually is
You tell ACAS you're thinking about making a tribunal claim. A conciliator then talks to you and to your employer separately, to see whether the dispute can be settled without a hearing.
It's free. It isn't a hearing, and it isn't an admission by anyone. Notifying ACAS is compulsory; taking part in the talks is voluntary, for both sides.
Be clear about what a conciliator is not. ACAS is impartial: they don't represent you, take sides, or tell you whether your case is strong. They explain the process and give an overview of the law. That's the boundary.
At the end you get an early conciliation certificate with a reference number. You need that number for the ET1 claim form. No certificate, no claim.
When you have to do it — and the few times you don't
The rule sits in section 18A of the Employment Tribunals Act 1996: before you present a claim you must give ACAS prescribed information about the matter, and s.18A(8) says you can't present it without the certificate. That covers the overwhelming majority of claims — unfair dismissal, discrimination, unlawful deduction from wages, whistleblowing, holiday pay.
The exemptions, in regulation 3 of the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) Regulations 2014, are narrow. The ones most likely to matter to a worker:
- Somebody else has already been through early conciliation about the same dispute and you're going on their claim form.
- Your employer contacted ACAS about the dispute first, and you haven't.
- You're bringing a dismissal claim with an application for interim relief — the urgent application to keep being paid while the case is decided. That has its own seven-day deadline and doesn't wait for conciliation.
If none of those describe you, assume you have to notify ACAS. ACAS won't tell you whether your claim is exempt.
How the pause works
Worth reading twice — this is where claims are lost on paperwork, not merit. The law uses two dates.
- Day A — the day you notify ACAS.
- Day B — the day you receive your early conciliation certificate.
Under section 207B(3) of the Employment Rights Act 1996, the stretch from the day after Day A up to Day B isn't counted when the tribunal works out whether you're in time. For discrimination claims the same machinery sits in section 140B of the Equality Act 2010. That's the pause.
There's a second protection on top. Under s.207B(4), if your deadline would have expired inside conciliation, it instead runs to one month after Day B. In ACAS's own words: at least one month from the date you received it.
The pause protects what's left, not what's gone.
Early conciliation stops the clock from the day you notify ACAS. It does not give back the time that passed before you picked up the phone.
Leave it until week eleven of a three-month window and eleven weeks are already spent. You'd have what remained, plus the one-month safety net after your certificate arrives — and nothing more.
It's your responsibility to notify inside your time limit. ACAS can't decide whether your claim is in time; only a tribunal can. Notify early — it costs you nothing.
Twelve weeks, since 1 December 2025
Early conciliation used to run for a maximum of six weeks. Before that, one month.
Since 1 December 2025 the maximum has been 12 weeks. The change was made in a single line by the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) (Amendment) Regulations 2025 (SI 2025/1153) — rule 6(1) of the 2014 rules, "six" becomes "12". It applies where you contacted ACAS on or after that date.
The good news: the pause on your deadline can now be twice as long. The catch: 12 weeks is a hard ceiling, not a schedule. The old power for a conciliator to extend by 14 days with both sides' agreement was removed in December 2020 and hasn't come back, so there's no extension mechanism. It can also end early — if the conciliator concludes settlement isn't possible, ACAS issues the certificate there and then and your clock restarts.
So you can't plan around a fixed 12 weeks. You might get four days of it.
What to have ready before you notify
The conciliator will ask what happened and what you want. Answering that from memory, under pressure, on a phone call is harder than it sounds. Have the dates in order — when it started, what was said, who was there, when you raised it, what your employer did next. Keep the letters, emails, payslips and rota screenshots somewhere private and off any work device.
Having that ready before the call is exactly what Stewrd is built to help with — not instead of ACAS, but so you're not reconstructing it from memory while the phone is ringing.
How this fits with the six-month change in October 2026
From 1 October 2026 the deadline for most tribunal claims goes from three months less one day to six months less one day — a separate change, made by the Employment Rights Act 2025 and the Employment Tribunal (Extension of Time Limits) (Miscellaneous Amendments and Transitional Provisions) Regulations 2026.
It doesn't replace early conciliation. The two work together: the longer window is the deadline, and conciliation still pauses it. But the six months isn't backdated. Under Reg 10 of those Regulations it applies only where the act you're complaining about — or the last act in a series — happened on or after 1 October 2026. If your situation began before then, you're still working to three months less one day, and conciliation is pausing that shorter clock. The full picture on the October 2026 change is here.
Turn up to that call with the record already made.
Stewrd is an AI workplace companion for UK workers — built by a former union rep and branch secretary. It explains where you stand in plain English and builds a private, dated record as you go, straight from your phone. Ready for ACAS, a rep or an adviser when it matters.
Know your rights. Record what matters.
Common questions
How does early conciliation pause the tribunal clock?
Day A is the day you notify ACAS; Day B is the day you receive your certificate. Under s.207B(3) of the Employment Rights Act 1996, and s.140B of the Equality Act 2010 for discrimination, the stretch from the day after Day A to Day B isn't counted.
What if I contact ACAS near the end of my time limit?
The pause only protects the time you still had left. Notify in week eleven of a three-month window and those eleven weeks are gone. You'd have what remained, plus the s.207B(4) safety net of one month from receiving your certificate.
Does early conciliation mean I have to settle?
No. Notifying ACAS is compulsory; taking part in the talks is voluntary, and so is any agreement. If you do sign a settlement — a COT3 — it's legally binding and you won't be able to take that case to a tribunal afterwards.
Where does this come from?
Employment Tribunals Act 1996, s.18A; Employment Rights Act 1996, s.207B; Equality Act 2010, s.140B; the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) Regulations 2014 (SI 2014/254) as amended by SI 2020/1003 and SI 2025/1153; and Reg 10 of the Employment Tribunal (Extension of Time Limits) (Miscellaneous Amendments and Transitional Provisions) Regulations 2026. All published on legislation.gov.uk.