Minimum Wage Underpayment 2026/27: How to Spot It and Claim Back Pay

Why your effective hourly rate can be lower than it looks

On paper, most underpayment isn't as obvious as an employer simply writing a lower hourly rate on your contract. It usually comes from what happens around the edges of your pay: hours that go unpaid, or costs that come out of your pocket, that legally should be factored into the National Minimum Wage calculation.

For National Minimum Wage purposes, your effective hourly rate is your total pay for a pay reference period (after excluding items like most deductions, unreimbursed job-related costs, and unpaid mandatory travel or training time) divided by the total hours you actually worked in that period. If that figure comes out below £12.71 for a worker aged 21 or over, you've been underpaid — regardless of what your contract says your hourly rate is.

Check your own numbers against the correct rate using

before assuming everything is in order.

Worked example 1: unpaid travel time between shifts

Leah works as a care worker on a contracted rate of £12.71/hour and is paid for eight-hour shifts, but isn't paid for the 30 minutes of mandatory travel time between two client visits each day.

Over a 22-day working month, that £6.36 daily shortfall adds up to roughly £139.92 in underpayment — money Leah is legally owed even though her contracted hourly rate is exactly at the National Living Wage. Multiply this over months or years of employment and even a small daily gap becomes a substantial claim.

Worked example 2: uniform costs eating into the minimum wage floor

Daniel, aged 22, earns exactly £12.71/hour and works 160 hours in a month, but his employer requires him to buy specific branded uniform items costing £45 with no reimbursement.

Even though Daniel's contract states £12.71/hour and his payslip shows that figure being paid, the compulsory, unreimbursed uniform cost reduces his effective pay for minimum wage purposes to £12.43/hour — below the legal floor. This is a genuine, common trap: employers often don't realise that job-related costs they require staff to bear can turn an apparently compliant wage into an underpayment.

Worked example 3: calculating back pay across several months

Priya discovers she's been underpaid by £0.35/hour for the last four months because her employer failed to apply the April 2026 rate increase from £12.21 to £12.71 promptly, working 150 hours a month.

Priya's employer owes her £300 in back pay for the four months the old rate was mistakenly still applied after the 1 April 2026 uprating. Notice that arrears use the rate that applied at the time of each underpayment — since the whole shortfall here relates to a single missed rate change, the calculation is simple, but where multiple rate changes are involved over a longer period, each month needs checking against the rate that applied then.

Routes to recovering underpaid minimum wage

Reporting suspected underpayment to HMRC via the ACAS helpline is confidential and doesn't require you to bring your own tribunal claim — HMRC can investigate an employer across its whole workforce, not just your individual case, which is often the most effective route where underpayment looks systemic rather than a one-off payroll error.

HMRC enforcement: what happens to employers who underpay

Once HMRC establishes minimum wage underpayment, it can order the employer to pay arrears to every affected worker, on top of a financial penalty calculated as a percentage of the underpayment owed to each worker, subject to a minimum penalty and an overall cap per worker. In serious or repeated cases, HMRC publishes the employer's name as part of its statutory "naming and shaming" scheme, which is a real reputational consequence many employers actively try to avoid.

It's unlawful for an employer to dismiss you or treat you badly for raising a minimum wage concern, whether informally, through ACAS, or via a tribunal claim — doing so is a distinct and serious legal wrong in its own right, on top of the underlying wage issue.

Bottom line

The 2026/27 National Living Wage of £12.71/hour is a legal floor, and it's calculated on your actual pay against your actual hours worked — not just the headline rate written into your contract. Unpaid travel time, mandatory training, and compulsory job-related costs are the most common ways an apparently compliant wage quietly falls below the legal minimum. Work out your effective hourly rate with

, cross-check your take-home figures with , and don't assume a correct-looking contract rate means you're actually being paid correctly.