The three-month rule for employment tribunal claims means you have three months minus one day from the event you are complaining about — your dismissal, an act of discrimination, an unlawful deduction from wages — to start a claim. Miss that window and a tribunal will usually refuse to hear the case, however strong it is on the merits. Before you file, you must also notify Acas to start early conciliation, which pauses the clock. The deadline is set to rise to six months under the Employment Rights Act 2025, expected to take effect in October 2026.1Acas. Employment Rights Act 2025
Which Claims the Three-Month Rule Covers
The three-month-minus-one-day deadline applies to the most common tribunal claims. Unfair dismissal under the Employment Rights Act 1996 must be filed within three months minus one day of the date your employment ended.2Legislation.gov.uk. Employment Rights Act 1996 – Section 111 Discrimination claims under the Equality Act 2010 run from the date of the discriminatory act and cover every protected characteristic, including age, disability, race, religion or belief, sex, sexual orientation, pregnancy and maternity, marriage and civil partnership, and gender reassignment.3Acas. If You’ve Been Discriminated Against at Work
Unauthorised deductions from wages — unpaid commission, withheld bonuses, missing holiday pay — fall under the same deadline, as do whistleblowing claims and employee breach of contract claims.4Acas. Employment Tribunal Time Limits
Claims That Get Six Months Instead
A smaller group of claims carries a six-months-minus-one-day deadline:
- Statutory redundancy pay, running six months from the date your job ends.5GOV.UK. Redundancy Your Rights – Statutory Redundancy Pay
- Equal pay, running six months from the end of your employment.
- Unfair dismissal related to strike action.
- Certain claims against a trade union.
- Certain claims by members of the armed forces.
For equal pay, a successful claim can recover arrears stretching back several years, but the filing window itself is still six months. File after six months minus one day and the tribunal can reject the claim entirely.4Acas. Employment Tribunal Time Limits
How to Calculate Your Deadline
Find your start date first. For unfair dismissal, the clock starts on the effective date of termination: the day your notice period expired if you were dismissed with notice, or the day your employment actually ended if you were dismissed without notice. For discrimination, it runs from the date of the discriminatory act. For wage deductions, it runs from the date of the deduction.6GOV.UK. Make a Claim to an Employment Tribunal – Time Limits
Then add three calendar months and subtract one day. Dismissed on 15 June? Three months on is 15 September; minus one day gives you a deadline of midnight on 14 September. The calculation is calendar-based, so the number of days in each month in between does not matter.4Acas. Employment Tribunal Time Limits
When the Deadline Falls on a Weekend or Bank Holiday
Under the Employment Tribunal Procedure Rules 2024, if the deadline lands on a Saturday, Sunday, Christmas Day, Good Friday, or a bank holiday, it rolls to midnight on the next working day.7Legislation.gov.uk. The Employment Tribunal Procedure Rules 2024 Treat that as a technical safety valve rather than a plan. Pinpoint the date early and file well before it arrives.
Continuing Acts of Discrimination
If you experienced a pattern of discriminatory behaviour rather than a single incident, the Equality Act 2010 may treat the whole pattern as a continuing act. The clock then runs from the most recent incident, not the first, but you have to show the earlier incidents were connected to the later ones to bring the whole course of conduct within time. The analysis often decides whether the claim is heard at all.
Acas Early Conciliation Comes First
You cannot file a tribunal claim without first contacting Acas to start early conciliation, a requirement introduced by the Enterprise and Regulatory Reform Act 2013.8Legislation.gov.uk. The Employment Tribunals (Early Conciliation: Exemptions and Rules of Procedure) Regulations 2014 – Explanatory Note You notify Acas of your intention to bring a claim and give your employer’s name and contact details. Acas then offers both sides a chance to settle without a hearing.9Acas. What Early Conciliation Is
Negotiating is voluntary; notifying Acas and getting the certificate is not. Without the certificate number, the tribunal will refuse your ET1 claim form.
How Early Conciliation Pauses the Clock
When you notify Acas, your filing deadline pauses. The pause runs from the day after Acas receives your notification (Day A) until the day Acas issues your certificate (Day B). Those days are not counted toward your three months.4Acas. Employment Tribunal Time Limits
There is also a minimum extension. If your original deadline would expire during conciliation or within one month after Day B, it is automatically pushed to one month after Day B. Say your original deadline was 10 June, you notified Acas on 1 June, and Acas issued the certificate on 8 July: your new deadline is 8 August. One condition is critical. You must notify Acas within your original time limit for the pause to apply at all.
If You Miss the Deadline
A missed deadline does not always kill the claim, but tribunals extend time reluctantly, and the test depends on the type of claim.
For unfair dismissal and most other statutory claims, you have to satisfy the “not reasonably practicable” test. That means showing it was not reasonably possible to file in time — serious illness, for example, or being misled by your employer about the deadline, or significant new information only emerging after time had run out — and that you then filed within a reasonable period once the obstacle was removed.2Legislation.gov.uk. Employment Rights Act 1996 – Section 111 Last-minute technical glitches or diary errors rarely persuade a tribunal.
For discrimination claims, the standard is broader. A judge can extend time if it is “just and equitable” to do so, weighing the length of the delay, the reason for it, and the effect on both sides.3Acas. If You’ve Been Discriminated Against at Work It is more flexible than the not-reasonably-practicable test, but it is still discretionary, not a right.
Filing the ET1
Once you have the Acas certificate, you file by completing the ET1 form. The online form on GOV.UK is fastest and gives you an immediate confirmation receipt. Paper is available but slower and can go astray in the post, which matters if the deadline is close.10GOV.UK. Make a Claim to an Employment Tribunal The form asks for your details, your employer’s name and address (which must match the Acas certificate), your dates of employment, the type of claim, and what happened. You have to include the Acas early conciliation certificate number or the form will be rejected. There is no fee.
What Changes in October 2026
The Employment Rights Act 2025 is set to raise the standard time limit from three months to six months, expected to take effect in October 2026 and to apply across claim types.1Acas. Employment Rights Act 2025 Until then, the three-month-minus-one-day deadline is binding. If your claim arises before the new rules take effect, do not assume the longer window applies — work from the current deadline and contact Acas as early as you can.