Can My Employer Make Me Work Unpaid Overtime?

Your employer can require unpaid overtime only if your contract allows it, and only within two legal limits. Your average pay for all the hours you work must not fall below the National Minimum Wage, and your working week must not go above an average of 48 hours unless you have agreed in writing. Outside those rules, a demand for unpaid overtime is a breach of your contract or of the law.

Start with your contract

There is no general legal right to be paid extra for overtime. Your contract decides whether overtime is required and whether it is paid. Many salaried contracts say you must work "such additional hours as are necessary" without extra pay. That wording can be lawful.

If your contract sets fixed hours and says nothing about overtime, your employer cannot simply require extra unpaid hours. If your contract promises overtime pay and it is not paid, that is an unlawful deduction from wages under section 13 of the Employment Rights Act 1996.

Check your contract, offer letter and staff handbook for the words "overtime", "additional hours" and "hours of work".

The minimum wage still applies

Unpaid overtime counts as working time. Under the National Minimum Wage Act 1998, you must be paid at least the minimum wage, on average, for all the time you work in each pay reference period. A pay reference period is usually your pay period, such as a week or a month, and cannot be longer than 31 days.

From 1 April 2026, the rates are:

1. £12.71 an hour for workers aged 21 and over (the National Living Wage)
2. £10.85 an hour for workers aged 18 to 20
3. £8.00 an hour for workers under 18 and apprentices who qualify for the apprentice rate

Here is an example. A retail assistant aged 24 is paid £476.63 a week for a 37.5 hour contract, which is exactly £12.71 an hour. Her manager asks her to stay late every night without pay, and she works 42 hours. Her pay now averages £11.35 an hour, which is below the National Living Wage. The employer owes her arrears for the shortfall, whatever her contract says.

You can complain to HM Revenue and Customs, which enforces the minimum wage and can order arrears and fines. You can also bring an Employment Tribunal claim for unlawful deductions under section 13 of the Employment Rights Act 1996.

The 48 hour limit

Regulation 4 of the Working Time Regulations 1998 limits your working week to an average of 48 hours, usually measured over 17 weeks. Overtime, paid or unpaid, counts towards this total. Your employer must keep records of hours worked.

You can choose to work more by signing an opt out. It must be in writing and it must be voluntary. Under regulation 5 of the Working Time Regulations 1998, you can cancel it by giving notice. The notice is seven days unless your agreement sets a longer period, which cannot be more than three months.

Some roles fall outside the 48 hour limit, such as those where you control your hours and your working time is not measured.

Refusing to sign the opt out

You do not have to sign an opt out. Under section 45A of the Employment Rights Act 1996, your employer must not subject you to a detriment for refusing to give up a right under the Working Time Regulations 1998. That includes losing shifts, being denied promotion or being disciplined. Under section 101A of the Employment Rights Act 1996, dismissing an employee for refusing is automatically unfair, and no qualifying service is needed.

Time limits

Acas states that time limits for employment tribunal claims increased from 3 months to 6 months on 1 October 2026. The 3 month limit may still apply to problems that started before 1 October 2026. Check your deadline early and seek advice. You must start ACAS Early Conciliation within that time. For a series of deductions, time usually runs from the last one.

What to do next

1. Read your contract for the clauses on hours and overtime.
2. Record your start and finish times every day, including breaks you work through.
3. Keep payslips and work out your average hourly pay for each pay period.
4. Do not sign an opt out unless you choose to.
5. Raise the issue in writing with your manager, then as a formal grievance if nothing changes.

The hours you record each day are the evidence for any claim, so keep them from today.

Frances N.U