Unlawful Deduction of Wages Claims 2026/27: How to Calculate and Bring One

What qualifies as an unlawful deduction

Under Part II of the Employment Rights Act 1996, your employer can only deduct from your wages, or withhold wages you're owed, if the deduction is required by law (PAYE, National Insurance, a court order), permitted by a specific written contract term, or covered by your genuine prior written consent given before the event that caused it. Anything outside those three routes is an unlawful deduction — and importantly, the same protection covers total non-payment, not just partial deductions. If your employer simply doesn't pay a bonus that met its contractual conditions, or short-pays your final salary on leaving, that's treated the same way as an unauthorised deduction.

Common examples include unpaid overtime that was worked and owed, a contractual bonus withheld without justification, holiday pay calculated incorrectly, and deductions for alleged mistakes or losses with no valid contractual basis. Use

to establish exactly what your correct net pay should have looked like — this becomes the baseline for any claim.

The three-months-less-one-day time limit

This is the single most important practical fact about these claims: you have three months less one day from the date of the unlawful deduction to start ACAS early conciliation. Miss it, and in most cases the claim is barred entirely, regardless of how clear-cut the underpayment is.

Worked example 1 — calculating the deadline

Priya's employer made an unlawful deduction from her wages on 10 March 2026.

Tribunals apply this deadline strictly. Extensions are only granted where it was "not reasonably practicable" to claim in time — for example, genuine ignorance of a deduction that only came to light later, not simply forgetting or being unsure how to proceed. If in doubt, starting ACAS conciliation early costs nothing and protects your position while you decide whether to proceed further.

Claiming for a series of deductions

Where deductions happen more than once — a persistent underpayment each pay period rather than a single event — the law allows you to treat them as a linked series. The three-month clock then runs from the date of the last deduction in that series, not the first, as long as the deductions share a common cause and aren't separated by significant gaps.

Worked example 2 — six months of underpayment

Tom was underpaid by £120 a month for six consecutive months due to his employer misapplying his pay band, with the final underpayment on 15 January 2026.

Because these are linked by the same underlying cause, Tom can claim the full £720 as long as he starts ACAS early conciliation within three months less one day of 15 January 2026 — not just the most recent £120. If there had been a large gap or an unrelated cause partway through, a tribunal might treat that as breaking the series, so it's worth setting out the pattern clearly in your claim.

How the claim amount is calculated

A tribunal award for unlawful deduction of wages is generally based on putting you back in the position you should have been in — the gross value of what was unlawfully withheld, translated into the net figure you'd actually have received after tax and National Insurance.

Worked example 3 — calculating net loss from a withheld bonus

Farah's employer withheld a £2,000 contractual bonus that met all its performance conditions. Her salary otherwise sits well within the basic-rate band.

Farah's claim would typically be framed around the gross £2,000 unlawfully withheld, with the tribunal ordering repayment and the usual PAYE tax and National Insurance treatment then applying — but for her own budgeting purposes, £1,440 is the realistic net figure she's actually out of pocket by. Check

alongside a tax calculation to get a precise net figure for your own case, since the split changes depending on where the withheld amount sits relative to the £50,270 higher-rate threshold.

The claims process step by step

Bottom line

An unlawful deduction of wages claim exists precisely for situations where an employer has taken money it wasn't entitled to, or withheld money it should have paid. The mechanics are straightforward once you understand them: work out the gross and net value of what's missing using

, check whether it's a single deduction or a linked series, and — critically — don't sit on it. The three-months-less-one-day time limit is unforgiving, and starting ACAS early conciliation costs nothing while protecting your right to claim.