Employment Tribunal deadline

Whistleblowing detriment time-limit calculator

A whistleblowing detriment complaint normally must be presented before the end of three months beginning with the act or failure to act, or the last in a series of similar acts or failures. ACAS Early Conciliation can alter the time limit.

Calculate this deadline

Rule reviewed 7 August 2026

At a glance

What the calculator applies

Period: Three months beginning with the relevant act, failure or last similar act
Trigger: Relevant act or deliberate failure to act, or the last in a series of similar acts or failures
Direction: Forward from the statutory act or failure date
Counting method: The calculator applies the corresponding-date rule used for the ordinary three-month ET period and collects ACAS Early Conciliation dates where they apply.

Free calculation

Calculate from the relevant date

The jurisdiction, forum and triggering event are preset for this deadline. Enter the date and any facts the calculator asks for.

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Jurisdiction

England & WalesBrowse jurisdictions

Court, tribunal or institution

Month-based limits use the corresponding-date rule (Pruden v Cunard Ellerman). ACAS Early Conciliation extends the limit under s.207B ERA 1996. From 1 December 2025, the EC period is capped at 12 weeks.

Claim type

Time limit

3 months less 1 day

Statute

s.48(3) ERA 1996

Trigger date

Act/failure to act

Extension test

Not reasonably practicable

Date of: Act/failure to act

ACAS Early Conciliation applies

Extends the time limit under s.207B ERA 1996

ERA 2025: limits will double from 3 to 6 months (commencement no earlier than October 2026). The qualifying period for unfair dismissal reduces from 2 years to 6 months from January 2027.

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Reviewed June 2026 · CPRReview coverage and exclusions

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Worked check

See what the calculator checks before it produces a date

Example input: 03/08/2026

Start with 03/08/2026 as the relevant act or deliberate failure to act, or the last in a series of similar acts or failures. The calculator applies the calculator applies the corresponding-date rule used for the ordinary three-month et period and collects acas early conciliation dates where they apply. and do not assume a weekend or bank-holiday extension for this statutory period. the calculator shows an acas adjustment only when the correct day a and day b dates are entered. before it shows the cited output and the checks that may change it.

Calculation basis

How the date is counted

The calculator applies the corresponding-date rule used for the ordinary three-month ET period and collects ACAS Early Conciliation dates where they apply.

Do not assume a weekend or bank-holiday extension for this statutory period. The calculator shows an ACAS adjustment only when the correct Day A and Day B dates are entered.

Check before use

Exceptions and matter facts

For an act extending over a period, section 48 treats the relevant date as the last day of that period; a deliberate failure has its own statutory treatment.
The Tribunal may allow a further reasonable period where it was not reasonably practicable to present the complaint in time. That discretion is not calculated automatically.

Check this result before using it

Deadline Engine is calculation software, not legal advice. Check the current rule, any order and the facts before adding a date to your diary.

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