UK · Employment rights

Constructive dismissal time limits

Constructive dismissal claims are won and lost on the calendar as much as the merits. The headline rule is three months less one day from your last day of employment. This page covers what that means in practice, how ACAS early conciliation moves the deadline, and the mistakes that cost claims.

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The headline rule

A constructive dismissal claim must be presented to the employment tribunal within three months less one day from the effective date of termination. The basis is section 111(2) of the Employment Rights Act 1996. The deadline applies to the moment the ET1 claim form is received by the tribunal, not the date you started drafting it.

The phrasing “three months less one day” is deliberate. If your last day of employment was 14 March, the deadline is 13 June. Missing by a single day is enough to defeat the claim.

Effective date of termination

The effective date of termination, defined in section 97 of the Employment Rights Act 1996, is the date your contract actually ended. In a constructive dismissal context, the position depends on how you resigned.

If you resigned with notice, the effective date is the end of the notice period, regardless of when you handed in the letter. So a four-week notice given on 1 March gives an effective date of 28 March (or 29 if the contract says calendar weeks), and the deadline is three months less one day from there.

If you resigned without notice (treating the contract as ended immediately because the breach entitled you to walk away), the effective date is the date of your resignation letter. The three-month clock starts then.

The final working day calculator will work out the effective date from your notice length and resignation date.

ACAS early conciliation — the stop-the-clock rules

Before bringing a tribunal claim you must notify ACAS for early conciliation. The notification freezes the clock for the duration of the conciliation period. Once ACAS issues the early conciliation certificate, the clock restarts.

The mechanics are set by section 207B of the Employment Rights Act 1996. Two dates matter. Day A is the date ACAS receives your notification. Day B is the date you receive the early conciliation certificate. The period between Day A and Day B does not count toward the three-month limit.

Two protective rules also apply. First, the claim cannot be presented to the tribunal before Day B. Second, the claimant always has at least one month after Day B to present the claim, even if the original three-month deadline would have fallen earlier.

Worked example

Suppose your effective date of termination is Monday 14 April. The original three-month deadline is Sunday 13 July. You notify ACAS on Monday 9 June (Day A). ACAS completes conciliation and issues the certificate on Wednesday 9 July (Day B).

The 30 days between 9 June and 9 July are stopped from the clock. The new deadline is Sunday 13 July plus 30 days, which is Tuesday 12 August. But the one-month-after-certificate rule also applies: you have at least until 9 August. The deadline is the later of the two, so 12 August in this example.

Always work the dates out twice. The interaction between the two rules catches people every year.

The limitation periods at a glance

Different employment claims have different limits. Knowing which apply matters when your situation could support more than one claim.

  • Unfair / constructive dismissal: three months less one day from the effective date of termination.
  • Discrimination: three months less one day from the act of discrimination (which is often the resignation date in a constructive dismissal context).
  • Unlawful deduction of wages: three months less one day from the deduction. A series of deductions has its own rules.
  • Breach of contract: heard at tribunal up to a £25,000 cap; six months from termination. Higher-value contract claims go to the county or high court with a six-year limit.
  • Redundancy pay: six months from the effective date of termination.

In a constructive dismissal context with discrimination undertones, both the three-month dismissal limit and the three-month discrimination limit are usually running at the same time from the same date.

When the tribunal will extend

The test for extension under section 111(2)(b) is that it was not reasonably practicable for the claim to be presented in time, and that it was then presented within a reasonable further period. The bar is high.

Reasons that have succeeded include serious illness or incapacity at the relevant time, being outside the UK with no realistic access to advice or the tribunal system, being misled by the employer about the dismissal date or the position generally, and physical impossibility (postal strikes, system outages on the day the claim was presented).

Reasons that have routinely failed include ignorance of the law, taking advice that turned out to be wrong, waiting for an internal appeal to conclude, choosing to negotiate a settlement that did not happen, and instructing a solicitor who missed the date.

Common mistakes

The mistakes below come up repeatedly. None of them look like obvious errors at the time, which is part of why they catch people.

The first is misreading the effective date of termination. If you give notice on 1 March and your contract notice is four weeks, your effective date is 29 March (or thereabouts), not 1 March. The clock runs from the end of the notice, not the start.

The second is waiting for the internal grievance or appeal to conclude before notifying ACAS. The internal process is not paused by tribunal proceedings, and the tribunal clock is not paused by the internal process. Notify ACAS in parallel.

The third is leaving ACAS notification until the last week. The conciliation period is up to six weeks. If you notify with a week to go, the clock stops, but the one-month-after-certificate rule then limits your buffer. Notify ACAS as soon as you have resigned.

The fourth is relying on solicitor capacity. Many employment-law solicitors are diary-bound and may not be able to take on an urgent case. If you instruct late, you may be told the firm cannot file in time. The tribunal does not accept “my solicitor was full” as a reason to extend.

The fifth is presenting the wrong claim form, or presenting on the wrong day because of a public holiday (the three-month deadline is calendar; it does not move to the next working day if the deadline falls on a bank holiday or weekend).

The safe sequence

The reliable approach is: as soon as you have decided to resign in response to a breach, write a short note of the chronology and the key dates. Resign with notice if you can; resign without notice only if the breach requires it. On the day you resign, work out the effective date of termination and the three-month deadline. Notify ACAS within seven days. Engage conciliation in good faith but be ready to present an ET1 the moment the certificate arrives.

Filing late is almost never recoverable. Filing on time, even with a thinner case, preserves the right to run the claim.

Useful calculators

Related reading

Frequently asked questions

What is the time limit for a constructive dismissal claim?
Three months less one day from the effective date of termination (your last day of employment). The deadline applies to the date the ET1 claim form is presented to the tribunal, not the date you instruct a lawyer or notify ACAS. The clock pauses during ACAS early conciliation. Missing the deadline almost always defeats the claim regardless of the underlying merits.
What is the effective date of termination?
For a constructive dismissal it is the date your employment actually ended. If you resigned with notice, it is the end of the notice period. If you resigned without notice in response to a breach so serious that you were entitled to walk away, it is the date your resignation letter was delivered. Get this date right; the time limit runs from it.
Does ACAS early conciliation extend the deadline?
Yes. The clock stops on Day A (the day ACAS receives your notification) and starts again on Day B (the day ACAS issues the early conciliation certificate). The conciliation period itself is up to six weeks. The minimum extra time given to claimants is at least one month after Day B, even if that pushes the deadline past the original three-month point.
Can the tribunal extend the deadline?
Only in narrow circumstances. The test is whether it was not reasonably practicable to present the claim in time. Reasons that have worked include serious illness, being out of the country with no internet access, and being misled by the employer about the dismissal date. Reasons that have not worked include ignorance of the law, waiting for an internal appeal, choosing a settlement route that fell through, and instructing a solicitor who missed the deadline.

General information about tribunal procedure, not legal advice. Time limits are strict and the tribunal rarely extends. For your specific situation, contact ACAS or an employment-law solicitor as soon as you decide to resign.