Paid below National Minimum Wage: how much you can recover

• Match your age (and apprentice status) to the correct legal rate for the period you worked. Rates change every April.
• Use the GOV.UK minimum wage calculator, then rebuild the arrears in pounds from your hours and rate.
• Raise it with your employer first where you can; keep a written trail.
• For formal enforcement, choose either an HMRC complaint or an employment tribunal claim for the same underpayment (Acas wording).
• Tribunal pay claims still sit inside strict personal time limits (today usually 3 months minus 1 day from the relevant underpayment, with a wider limit for most claims if the clock starts on or after 1 October 2026).

GOV.UK explains that the hourly rate depends on your age and whether you are an apprentice. You must be at least school leaving age to get the National Minimum Wage, and aged 21 to get the National Living Wage. Workers aged 20 and under still get the minimum wage rates for their band.

Apprentices get the apprentice rate if they are under 19, or 19 or over and in the first year of the apprenticeship. Once an apprentice aged 19 or over has finished the first year, they move onto the minimum wage for their age.

The National Minimum Wage Act 1998 sits behind these rights. Day to day, use GOV.UK rates and the Acas NMW guides rather than trying to interpret the Act alone.

Rates change on 1 April every year. Always check the current table on GOV.UK: https://www.gov.uk/national-minimum-wage-rates

From April 2026:

Previous rates, April 2025 to March 2026:

If your underpayment straddles April, split the hours by period. Do not apply £12.71 to March 2026 hours, and do not leave April 2026 hours stuck on £12.21.

You are 28. From April 2026 your legal rate is £12.71 an hour (NLW). Your employer still pays £11.50. In one month you work 160 hours.

• Legal pay: 160 x £12.71 = £2,033.60
• Actual pay: 160 x £11.50 = £1,840.00
• Gross arrears for that month: £193.60

That is one month only. If the same rate error ran for six months at similar hours, the gross shortfall approaches £1,161.60 before you even look at earlier periods on the old £12.21 rate.

Cross-check with the official calculator on GOV.UK (linked from the rates page and from https://www.gov.uk/guidance/calculating-the-minimum-wage). The calculator helps you spot whether allowances, unpaid working time, or the wrong pay reference period are dragging you under the floor.

Acas is blunt: it is against the law to pay less than the NMW or NLW. Employers must keep accurate pay records and make them available when requested. If they underpaid, they should resolve it as soon as possible, including backdated non-payment, even if you no longer work there.

Start informally where it is safe to do so. Show the calculator result, your age band, your hours, and the rate on the payslip. If that fails, raise a grievance. Acas notes that a grievance can resolve matters without legal action, but it does not replace the need to watch enforcement deadlines if you later go to a tribunal.

Acas says that if you cannot resolve the issue, you can either:

• complain to HM Revenue and Customs (HMRC), or
• make a claim to an employment tribunal

You must choose one route for the same issue. You cannot take the same underpayment through both legal processes.

HMRC route (in outline)

• Complaints to HMRC can be anonymous. A friend, family member or colleague can also complain.
• If HMRC finds underpayment, it can issue a notice to pay money owed, going back a maximum of 6 years.
• HMRC can also issue a fine of up to £20,000 and a minimum of £100 for each worker affected, even if the underpayment itself is smaller.
• HMRC may take further legal action, including criminal proceedings in some cases, and names can be passed on for a public naming list.

You can complain using the pay and work rights form on GOV.UK (https://www.gov.uk/pay-and-work-rights) or by contacting the Acas helpline.

Tribunal route (in outline)

• You control the claim yourself (or with advice), subject to Acas Early Conciliation first for most claims.
• Acas explains that how much you can claim depends on the type of claim. For a claim about non-payment of the minimum wage, Acas guidance commonly frames tribunal recovery as going back up to 2 years, subject to the series rules below.
• Time limits are personal and strict:
• one underpayment: 3 months minus 1 day from the date you should have been paid
• several wrong underpayments in a row: 3 months minus 1 day from the most recent wrong deduction
• Acas says you can often claim up to 2 years back if there is less than 3 months between each underpayment, or the underpayments are linked (for example the same rate error). Treat that as Acas guidance on how series claims are commonly framed, not as a guarantee for every fact pattern.

Remember the October 2026 change on Acas's time-limits page: from 1 October 2026, most claims move to 6 months minus 1 day if the time limit starts on or after that date. Grievance does not pause the clock. Notifying Acas in time for Early Conciliation can.

Acas also covers detriment. Your employer must not treat you worse for becoming entitled to a higher minimum wage rate or for asserting your right to the minimum wage. Examples can include bullying, turning down training without good reason, or cutting hours without good reason. Dismissal connected to asserting minimum wage rights can be automatically unfair for employees. Workers who cannot claim unfair dismissal may still be able to claim detriment. Get advice if retaliation starts.

• Using the wrong age band. Turning 21 changes the legal floor. Apprentice status can change it again after year one.
• Forgetting April uplifts. A rate that was lawful in March can be unlawful in April.
• Counting only cash hourly pay. Some deductions, unpaid time, or "training" arrangements can push effective pay under the minimum. Use GOV.UK calculating guidance rather than guessing.
• Running HMRC and tribunal on the same shortfall. Acas says you must choose.
• Missing the tribunal clock while waiting for HMRC. Different routes, different controls. If you want a tribunal claim, diary Acas notification yourself.
• Confusing the Real Living Wage with the legal NLW. The Real Living Wage is a voluntary campaign rate. The legal floor is the GOV.UK NLW/NMW table.

Before you complain or claim, get the arithmetic straight. Paye Mes Heures can help you estimate underpayment across months and assemble a dossier of hours, rates and shortfalls you can attach to an employer email, an HMRC complaint, or Early Conciliation notes. It does not replace HMRC, Acas, or a tribunal, and it is not a full UK enforcement simulator. Pair it with the official calculator and the Acas pages linked below.

If the rate on your payslip sits under the legal floor, the arrears are not a tip. They are wages the law already priced.

• Acas - If an employer does not pay minimum wage: https://www.acas.org.uk/national-minimum-wage-entitlement/if-an-employer-does-not-pay-minimum-wage
• GOV.UK - National Minimum Wage and National Living Wage rates: https://www.gov.uk/national-minimum-wage-rates
• National Minimum Wage Act 1998: https://www.legislation.gov.uk/ukpga/1998/39/contents
• GOV.UK - Calculating the minimum wage: https://www.gov.uk/guidance/calculating-the-minimum-wage
• GOV.UK - Pay and work rights complaints: https://www.gov.uk/pay-and-work-rights
• Acas - Employment tribunal time limits: https://www.acas.org.uk/employment-tribunal-time-limits