What has to happen between an ET1 arriving and the ET3 response being due, and what happens on the day after that if nothing has been filed.
An email arrives from the tribunal's online service, or a letter lands at the registered office, and inside is a claim form headed ET1. Somewhere in it is a name you recognise — a former employee, set out section by section: what they say happened, what they are claiming, and what they want. Reading it tells you nothing about what to do next, only that something is now running against a clock whether you have decided how to respond to it or not.
That clock is 28 days, and it started the day the tribunal sent you the claim. The day it was opened here is irrelevant to it.
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Rule 16 of the Employment Tribunals Rules of Procedure 2013 — Schedule 1 to the Employment Tribunals (Constitution and Rules of Procedure) Regulations 2013, SI 2013/1237 — sets the response period at 28 days from the date the tribunal sent the claim form to you. That date is printed on the covering letter or email, and it is what starts the clock. The date it reached your desk, your inbox, or a registered office, comes later, and any gap between the two is time already used up.
The 28 days are for more than filling in a form. In that window you need to establish who dealt with the employee, what the file shows, whether the claim is one you intend to resist in whole or in part, and what it would cost to settle it compared with defending it to a hearing. Leaving the file-gathering until the deadline is close is the single most common reason a response arrives thin, or late.
The response goes in on the prescribed ET3 form, through the tribunal's online response service, by downloading and posting the paper form, or through a legal representative's MyHMCTS account. It has to say your name and address and whether you intend to resist all, part, or none of the claim. The grounds of resistance decide the case: your account of what happened, addressed allegation by allegation, with dates and facts. A response that disputes everything without saying why gives a judge very little to set against a detailed claim. Tribunal defence at a fixed fee per stage covers what is involved in building that response, from the first read of the claim through to a hearing if the case gets that far.
A made-up scenario, showing how the 28 days get used. A six-person marketing agency dismisses an account manager after a short disciplinary process over a missed client deadline. Six weeks later, an ET1 for unfair dismissal arrives, sent by the tribunal on a Tuesday. The clock now reads 28 days from that Tuesday. In the first week, the owner pulls the file: the disciplinary invite, the notes from the hearing, the outcome letter and the contract setting out notice terms. In the second week, a decision gets made on whether the process followed was defensible or whether settling makes more sense than defending it — a question that is cheaper to answer early than after a response has already been filed. By day 20, the ET3 is drafted with the dismissal process set out date by date, and it goes in with a week to spare, leaving room to fix anything the tribunal queries about the form itself.
Rule 21 covers what happens next. An employment judge looks at what the claimant has put in and decides whether the claim, or part of it, can be determined on that material alone. Where it can, a judgment is issued against the employer, sometimes without any hearing at all. That judgment can decide liability and compensation using only the claimant's version of events, including points the employer would have disputed, simply because nothing was said on the other side in time. A business with a real defence can still lose entirely for having filed nothing.
Rule 20 allows a written application for an extension, copied to the claimant, setting out the reason more time is needed. Made before the 28 days run out, it is a straightforward request for a judge to consider. Made after the deadline has passed, it has to be accompanied by a draft of the response the employer wants to present, or an explanation of why that cannot be provided yet, and a judge then decides whether to allow it at all. An extension is not automatic, and it should not be assumed granted until the tribunal confirms it in writing. Work on the ET3 itself should continue in parallel while that answer is awaited.
Most claimants have to contact Acas before an ET1 can be presented to a tribunal at all, so a notification from Acas is normally the first sign of a dispute, often weeks ahead of any claim form. Since 1 December 2025, under the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) (Amendment) Regulations 2025 (SI 2025/1153), that early conciliation period runs for up to 12 weeks, doubled from the previous six. A settlement reached during that window, through a settlement agreement, ends the matter without a claim ever being issued, and without the 28-day response process starting at all. An Acas notification carries the same urgency as an ET1 itself.
Where the claim follows a disciplinary process, preparing for a dispute covers the evidence a tribunal weighs before this stage is reached.
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28 days. Rule 16 of the Employment Tribunals Rules of Procedure 2013 (Schedule 1 to SI 2013/1237) requires the response, on the prescribed ET3 form, to be presented to the tribunal within 28 days of the date the tribunal sent you the claim. The same 28-day period applies whether the claim is for unfair dismissal, discrimination, unpaid wages or anything else an employment tribunal hears, and whether you intend to resist all of it, part of it, or none of it.
The date on the tribunal's own covering letter or email. That is the date it sent you the claim form, and it is what starts the 28 days. The date it arrived on your desk or in your inbox is a separate date and does not move the deadline. If post at a registered office sits unopened for a few days, or an email sits unread, the clock keeps running from the date the tribunal sent it, and that gap is lost time you do not get back.
Under rule 21, an employment judge decides whether the claim can be determined on the material the claimant has already put in, with no response from you to weigh against it. Where it can, a judgment is issued against you, sometimes without a hearing at all, covering both liability and the amount of compensation. That can mean a case decided on the claimant's account alone, including facts you would have disputed, simply because nothing was said on your side in time. Once a default judgment has been made, overturning it is a separate and much harder application than filing the ET3 on time would have been.
Yes, under rule 20, but it has to be a written application to the tribunal, copied to the claimant, setting out the reason more time is needed. Asking before the 28 days run out is straightforward. Asking after they have expired is harder: the application then has to come with a draft of the response you want to present, or an explanation of why you cannot provide one, and an employment judge decides whether to grant it. Do not treat an extension as granted until the tribunal confirms it in writing.
Usually, yes. Acas early conciliation is a required step before most claims can be presented to a tribunal at all, so a notification from Acas is normally the first sign a dispute is heading that way, often weeks before any ET1 is issued. Since 1 December 2025, under the Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) (Amendment) Regulations 2025 (SI 2025/1153), that conciliation window runs for up to 12 weeks. It was six weeks before that change, so there is more time now to settle before a claim form is ever served.
Your name and address, whether you intend to resist all or part of the claim, and — this is the part that decides the case — your grounds of resistance. That means answering each allegation in the ET1 with your own version of events, supported by dates and facts. A general denial on its own carries little weight. A thin ET3 that disputes everything without saying why gives a judge very little to weigh against a detailed claim, so the time spent assembling the file before you respond pays off when the claim is detailed.
Cost out both options before deciding. Defending to a final hearing takes months and the time of whoever runs the business, on top of any fee for doing it. A settlement agreement ends the matter on agreed terms and does not require either side to admit liability. Which one makes sense depends on the claim, the evidence and what you are being asked to pay to end it, and that costing is best done in the first days of the 28. Doing it in the last few days leaves no time to act on the answer.
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