Underpayment Formal Complaint Letter Template & Generator

If you need to formally complain to your employer about being paid below minimum wage, a written letter is the recommended first step — it creates a clear record and shows you're pursuing the matter formally. Below is what a strong underpayment formal complaint should include, plus a free tool to generate yours.

What this letter needs to cover

• State the correct NMW rate for the workers age and category
• Calculate the underpayment with figures
• State this is unlawful under the National Minimum Wage Act 1998
• Request immediate correction and repayment of arrears
• Warn that failure to correct may result in a report to HMRC

Calculating whether you're genuinely being underpaid

Minimum wage underpayment isn't always obvious from your payslip alone — it can result from unpaid trial shifts, mandatory unpaid training, deductions for uniform or equipment that take you below the threshold, or simply an hourly rate that's below the correct rate for your age band.

What to include before you send it

• Your age band and the correct minimum wage rate that should apply
• Your actual hourly rate, and how you've calculated the shortfall
• The period you believe this has been happening
• A request for back payment of the difference

Deductions that can push you below minimum wage without you realising

Certain deductions — for example, for uniform costs where you're required to buy your own from a specific supplier — can effectively reduce your pay below minimum wage even if your headline hourly rate looks correct. It's worth checking your actual take-home pay against hours worked, not just your stated rate.

Frequently Asked Questions

How far back can I claim underpaid wages?
Claims for unlawful deduction from wages generally need to be brought within 3 months minus 1 day of the last deduction, though a series of deductions can sometimes extend this — it's worth acting promptly regardless.

What if my employer says apprentices or under-21s are paid differently?
Different minimum wage rates do apply by age band and for genuine apprentices in their first year — it's worth confirming which specific rate should apply to your situation.

See our full letter template & generator library for related letters, or use our free checkers for guidance specific to your situation.