What is the deadline for whistleblowing detriment claim?
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 your deadline
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Worked example
- Example input
- 03/08/2026
- Expected result
- Monday 2 November 2026
The detriment occurred on Monday 3 August 2026, before any ACAS adjustment.
The ordinary three-months-less-one-day period ends on 2 November. A continuing act, later act or ACAS Early Conciliation can change the calculation.
How this deadline is counted
- 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.
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.
Employment Rights Act 1996, section 48. Employment Rights Act 1996, section 48(3) and (4). Employment Rights Act 1996, section 48 checked 07/08/2026
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.
Deadline Engine is calculation software, not legal advice. Check the current rule, any order and the facts before adding a date to your diary.