HMRC National Minimum Wage complaint vs tribunal : check underpayment and recover what you are owed

• Paying below National Minimum Wage / National Living Wage is unlawful. Employers must also fix backdated non-payment, even after you leave.
• For the same underpayment, Acas says choose either an HMRC complaint or an employment tribunal claim, not both.
• HMRC can require arrears going back a maximum of 6 years, issue penalties (GOV.UK: up to 200% of arrears, capped at £20,000 per worker; Acas also notes a minimum fine framing of £100 per worker affected), and may trigger naming / further enforcement.
• Tribunal claims have strict personal time limits (most: 3 months minus 1 day now; from 1 October 2026 most become 6 months minus 1 day if the clock starts on/after that date) and Acas guidance on recovering roughly up to 2 years of linked underpayments (nuance, not a guarantee).
• HMRC complaints can be anonymous; third parties can complain too. Tribunal claims put you on the claim form as claimant.
• Start by checking hours and pay with the GOV.UK calculator, then raise it with the employer if safe, then choose the enforcement route.

National Minimum Wage rules look at pay reference periods, which hours count, and which payments count. Tips, for example, do not shore up the wage for NMW purposes. From April 2026 the headline adult rate (21+) is £12.71. Younger ages and apprentices have different bands: always re-check GOV.UK rates for your birthday band.

GBP example: You are 32 and work 40 hours. Legal floor: 40 × £12.71 = £508.40. Employer pays £480 basic and says £40 of card tips "make up" the rest. Tips do not count toward NMW. You are £28.40 short for that week on wages alone, even though £480 + £40 = £520 on a till report.

GBP example (unpaid minutes): Same 40 rostered hours, but you stay 20 minutes unpaid to close three nights a week. Extra time: 3 × 0.333… ≈ 1 hour. True hours ≈ 41. Pay still £508.40 for NMW floor on 40 hours? No: 41 × £12.71 = £521.11. If you only received £508.40, the shortfall is about £12.71 that week from unpaid closing alone.

Keep a week-by-week table before you choose a route. Both HMRC and a tribunal expect coherent figures.

HMRC enforces the minimum wage for the Department for Business and Trade. Investigations can follow a worker complaint (via Acas or the GOV.UK pay and work rights channels), third-party information, or HMRC's own risk targeting.

What HMRC can do

If HMRC finds underpayment, officers may:

• issue a notice of underpayment requiring arrears to named workers, with arrears calculated under the statutory formula (often using current rates for the relevant age band, which can increase what is owed compared with the historic shortfall)
• require payment of a financial penalty: GOV.UK states up to 200% of the arrears, maximum £20,000 per worker, with a 50% reduction if the employer fully complies within 14 days of the notice
• take further civil or criminal steps in serious cases
• support the wider naming / publicity process through government channels (Acas describes names being passed for a public list)

Acas summarises HMRC powers in worker-facing language: notice to pay money owed going back a maximum of 6 years; fines described with a minimum of £100 and up to £20,000 for each worker affected; possible legal action including criminal proceedings.

Practical upsides of HMRC

• Longer look-back in enforcement (up to 6 years of arrears on a notice) compared with the typical tribunal wages window discussed below.
• You can complain anonymously, and a friend, relative or colleague can complain as a third party.
• HMRC can inspect records, interview, and compel information. The burden in civil NMW disputes sits heavily on the employer to show the minimum was paid.
• Penalties and naming create pressure that a private settlement talk may lack.

Practical downsides / limits

• You do not control the pace or priorities of an investigation.
• If you later (or first) take your own tribunal or court claim on the same underpayment, GOV.UK says HMRC will not continue to act on your behalf for that issue.
• Anonymity can be hard to preserve in a tiny workplace even if the form allows it.
• HMRC deals with minimum wage enforcement. Pure contractual premiums above NMW, or some holiday-pay arguments that are not NMW shortfalls, may need a different path.

You can claim in an employment tribunal to recover money owed because you were not paid the minimum wage (and related detriment / dismissal claims may also be available if you were punished for asserting the right).

Time limits (personal clock)

Acas NMW guidance:

• 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

Remember the dual regime on Acas's time limits page (updated 4 September 2026): from 1 October 2026, most claims become 6 months minus 1 day if the time limit starts on or after that date. Earlier start dates keep the shorter most-claims limit. Grievance processes do not pause the clock; notifying Acas for Early Conciliation in time can.

Northern Ireland uses industrial tribunals; this article follows the Great Britain framing.

How far back can tribunal recovery go?

Acas tells workers that for a minimum wage tribunal claim you can claim money owed going back 2 years, and that you can claim up to 2 years back if either:

• there is less than 3 months between each underpayment or non-payment, or
• the underpayments are linked (for example the same error)

Treat that as Acas guidance, not a personal guarantee that every historic month will be awarded. Employment Rights Act 1996 section 23 also contains a two-year restriction for many unlawful deduction complaints. Litigation about the edges of that backstop has been active; do not write your own case theory from headlines. If your arrears are old and large, factor that uncertainty into the HMRC vs tribunal choice and get advice.

Other tribunal features

• You must usually notify Acas for Early Conciliation first.
• You are a named claimant; the process is yours to progress.
• Remedies centre on what you are owed (and related awards if other claims succeed). HMRC-style penalties against the employer are not the same toolset.
• GOV.UK notes that in civil NMW cases the employer must prove the minimum was paid.

Rough decision sketch (not advice): Long pattern of NMW underpayment over several years, small workplace fear of being named on a claim form, and a clean NMW maths case → many workers look at HMRC first. Fresh underpayment, mixed contractual and NMW issues, need for Early Conciliation leverage on a COT3, or detriment for asserting NMW rights → tribunal (or tribunal-related claims) may fit better. Borderline files deserve a short advice call before you lock a route.

1. Run the GOV.UK NMW calculator and keep screenshots.
2. Export payslips, rotas, clock data, and messages.
3. Raise the issue informally in writing if you can do so safely; Acas still encourages trying to fix it with the employer.
4. Consider a formal grievance (knowing it does not stop tribunal clocks).
5. Call the Acas helpline (0300 123 1100) for process questions; complex NMW queries can be passed toward HMRC's NMW team.
6. Only then submit the pay and work rights complaint or start Acas Early Conciliation toward a tribunal claim.

• "I'll do HMRC and tribunal together for the same shortfall." Acas says choose one legal process for that issue; GOV.UK says your own claim stops HMRC acting for you on it.
• "Tips cover the NMW gap." They do not count toward NMW pay.
• "My grievance buys me six months." It does not pause the tribunal limit.
• "HMRC always names my boss next week." Naming and penalties follow HMRC's enforcement policy; timelines vary.
• "Acas's 2 years is automatic." It is guidance tied to linkage / spacing; tribunals apply the law to facts.
• "I left years ago, so nothing can be done." Employers must still resolve backdated NMW non-payment; HMRC's six-year arrears reach can still matter.

Whichever door you open, the file is only as strong as the hours and pay trail behind it. Paye Mes Heures helps you build that trail in pounds and hours so you can compare an HMRC-style multi-year pattern with a tighter tribunal window before you commit. Then use Acas, GOV.UK complaints, or Early Conciliation as the official next step.

• https://www.acas.org.uk/national-minimum-wage-entitlement/if-an-employer-does-not-pay-minimum-wage
• https://www.gov.uk/guidance/calculating-the-minimum-wage/enforcing-the-minimum-wage
• https://www.gov.uk/pay-and-work-rights
• https://www.acas.org.uk/employment-tribunal-time-limits
• https://www.gov.uk/national-minimum-wage-rates