From informal complaint to tribunal: a practical unpaid-hours roadmap
End-to-end unpaid hours path: check figures, raise with your employer, grievance, Acas Early Conciliation, then ET1. Dual tribunal time limits, GBP examples at £12.71, and an honest Paye Mes Heures dossier tip.
Unpaid hours rarely arrive as one dramatic event. They creep in: unpaid closing, skipped training pay, overtime that never hits the payslip. The law gives you a path from a quiet chat with payroll to an employment tribunal claim. Miss a step or a deadline and a strong file can still fail on timing.
This roadmap follows Acas's unpaid wages guidance, Early Conciliation rules, and GOV.UK's make-a-claim pages. It is a practical sequence for Great Britain (England, Scotland and Wales). Northern Ireland uses a different industrial tribunal system.
In short
- Start with hard figures: hours worked, hours paid, rate, and shortfall in GBP.
- Raise the problem with your employer informally in writing, then use a formal grievance if needed.
- Grievance does not pause tribunal time limits. Diary the clock from day one.
- Dual primary limits apply: most claims 3 months minus 1 day now; from 1 October 2026 most become 6 months minus 1 day if the clock starts on or after that date.
- Notify Acas for Early Conciliation inside that limit, then present form ET1 with your certificate if talks fail.
- Use tools to estimate and prepare a dossier. Do not treat a French-facing product as a finished UK tribunal simulator.
Step 1: check your figures
Acas's unpaid wages guide starts here for a reason. Before you accuse anyone of anything, work out:
- how much you think you should have been paid (after lawful deductions)
- when you should have been paid
- how much you actually received
Pull your payslips, written statement / contract, bank credits, rotas, timesheets, and any messages about hours. Note the pay period each slip covers and whether overtime or training needed approval.
GBP example: From 1 April 2026, workers aged 21+ must get at least £12.71 an hour for National Minimum Wage / National Living Wage purposes. You are rostered 38 hours but stay 2 unpaid hours to close three nights a week. Extra time ≈ 6 hours a week. At £12.71 that is about £76.26 a week of unpaid work if those hours should count. Over four weeks: about £305. Write the week-by-week table before you email HR.
If the issue is minimum wage (average pay too low once unpaid hours count), run the GOV.UK NMW calculator and keep screenshots. If it is contractual overtime above the floor, keep the contract clause beside the rota.
Step 2: raise it informally
Acas says it is usually best to raise unpaid wages informally first. Talk to your manager, payroll, or HR. Confirm the conversation in an email or letter so you have a record.
Acas suggests you:
- explain how much you think you are owed and why
- show your calculations
- share evidence (payslips, contract, timesheet, roster, written agreements)
- ask for a response within a set time (for example within 7 days, or before the next payday)
Keep the tone factual. Attach the spreadsheet. Ask for a written correction and back pay by a named date.
If it is a minimum wage issue and the employer does not fix it by the next payday, Acas notes they could be breaking minimum wage law, and you have other formal options (including HMRC). For the same NMW underpayment you generally choose HMRC or tribunal later, not both.
Step 3: formal grievance
If informal talks stall, raise a grievance: a formal complaint under your employer's policy (or a clear written complaint if there is no policy). Judges often expect you to have tried to resolve the dispute; skipping that can affect compensation even if you win.
Critical: Acas's time limits page is blunt. Going through grievance, disciplinary or appeal procedures does not change your tribunal time limit. If HR takes eight weeks, Clock A keeps moving. Diary Early Conciliation now, not after the appeal hearing.
Step 4: map the dual tribunal time limits
For pay and wages claims, Acas says:
- one underpayment: 3 months minus 1 day from the date you should have been paid
- several underpayments: 3 months minus 1 day from the last time it happened
From 1 October 2026, the limit for most claims becomes 6 months minus 1 day, but only if your time limit starts on or after 1 October 2026. Clocks that started earlier keep the shorter most-claims rule.
Worked dual-regime example: Last unpaid payday 10 September 2026 → Regime A (3 months minus 1 day) → ordinary end 9 December 2026. Last unpaid payday 10 October 2026 → Regime B for most claims (6 months minus 1 day) → ordinary end 9 April 2027.
Acas also explains that for unpaid wages you can often claim up to about two years back if gaps between underpayments are under three months or the underpayments are linked. That is look-back guidance, not a licence to ignore the filing deadline. How far back sums go is separate from when you must start.
Aim to notify Acas well before 11:59pm on the last day.
Step 5: Acas Early Conciliation
Before most employment tribunal claims you must notify Acas. Acas then offers Early Conciliation.
What Early Conciliation is for:
- a structured chance to settle without a hearing
- a conciliator speaking to each side separately
- a COT3 settlement if you agree (legally binding)
- an Early Conciliation certificate if you do not settle, which you need for ET1
What Acas cannot do during Early Conciliation (Acas's own list):
- represent you
- take sides
- prepare your tribunal case
- tell you if you have a valid claim
- give legal advice
Early Conciliation should not be your first step. Try informal resolution and grievance first where you can. But do not wait for those processes if Clock A is about to expire: notify Acas inside the limit. If you notify in time, the tribunal time limit is paused until Early Conciliation ends. Notify late and you do not get that pause.
Bring your pound schedule into conciliation. "They owe me roughly something" stalls talks; "£305 for four weeks of unpaid closing at £12.71 × 6 hours" moves them.
Step 6: make the claim (ET1)
If Early Conciliation ends without settlement, GOV.UK explains how to claim:
- online (usual route) or by post on the claim form
- for yourself, with others treated the same way, or as a representative
- you usually need an Early Conciliation certificate number for each respondent
- there is no fee to make a claim (you may still face other costs if you act unreasonably)
Before you start, gather claimant and respondent names and addresses (job offer, contract, payslips) and your certificate numbers.
After a timely Early Conciliation, Acas guidance is that you will have at least one month from receiving the certificate to present the claim; sometimes longer. Working it out can be complex. Only a tribunal finally decides whether a claim is in time. Diary the certificate date the day it arrives.
Present a coherent claim: dates, hours, rates, shortfall, and what you want (payment of wages owed). Attach or be ready to produce the evidence list from Step 1.
Optional fork: HMRC for National Minimum Wage
If unpaid hours pull you under the NMW / NLW floor, you can complain to HMRC instead of taking a tribunal claim on that same underpayment. HMRC can require arrears going back up to 6 years and may issue penalties. Acas says choose one legal process for the same minimum wage issue. Factor that choice before you lock ET1 language on pure NMW arrears.
Roadmap checklist
- Build the hours/pay table (GBP).
- Informal written raise with a response deadline.
- Formal grievance if needed (clock still running).
- Calculate Clock A under the dual regime; diary Acas notification.
- Notify Acas; engage Early Conciliation with figures ready.
- Settle on COT3 or present ET1 with certificate in time.
- Keep every email, rota, and payslip until the case ends.
Common traps
- "I'll finish the grievance first, then think about Acas." The filing clock does not wait.
- "Counting 90 days is fine." Use calendar months minus one day the way Acas illustrates.
- "1 October 2026 lengthens my September underpayment." Only clocks that start on/after that date get the new most-claims six-month rule.
- "Early Conciliation is free legal advice." Conciliators are impartial and cannot advise on prospects.
- "Paye Mes Heures will file my ET1." Use it to estimate hours and prepare a dossier; Acas and GOV.UK remain the official claim path.
- "I can do HMRC and tribunal together for the same NMW shortfall." Acas says choose one process for that issue.
Soft next step
The roadmap only works if the maths is tidy. Paye Mes Heures can help you estimate unpaid hours and prepare a dossier in pounds and dates before you email payroll or notify Acas. It is a preparation aid, not a substitute for Early Conciliation, GOV.UK's claim form, or advice on tight limitation dates. When your table is ready, follow Acas and GOV.UK for the official next click.