Unpaid overtime obligations

Short answer

In many cases yes, an employer can require you to work overtime and there is no automatic legal right to be paid for it. Whether overtime is compulsory, and whether it must be paid, depends mainly on your contract of employment. But there are important limits: your average pay across the hours you actually work must not fall below the National Minimum Wage, and your total working hours are subject to the Working Time Regulations 1998.

Does your contract require overtime?

The starting point is your written contract and the written statement of employment particulars your employer must provide. You are generally only obliged to work overtime if your contract requires it, either expressly or through a term that has become part of the contract (for example through a staff handbook incorporated into your contract, or a long-standing custom and practice).

If your contract is silent, or only permits the employer to request overtime, you are usually not obliged to work more than your contracted hours. If it contains a clear compulsory overtime clause, you can normally be required to work reasonable additional hours.

Contract terms usually fall into recognisable categories. Compulsory overtime means you must work it if asked. Voluntary overtime means the employer offers and you can decline. Non-guaranteed overtime means you are not guaranteed the hours, but must work them if offered. The label used in your contract matters, so check the precise wording.

Does overtime have to be paid?

There is no freestanding legal right to extra pay simply because you worked beyond your normal hours. Employers do not have to pay a premium (such as time-and-a-half) unless the contract provides for it. So “unpaid overtime” is lawful in principle if your contract genuinely provides that additional hours are unpaid, or if you are on a salary that is expressed to cover the hours actually required.

The key protection is the National Minimum Wage. Your total pay divided by your total hours worked (including the overtime) must not drop below the applicable minimum wage rate. If working unpaid extra hours pushes your effective hourly rate below the National Minimum Wage or National Living Wage, that is unlawful, and the employer must make up the shortfall. This is the most common way that “unpaid overtime” becomes illegal in practice, and it particularly affects salaried staff whose salary, once spread over long hours, falls below the minimum.

Working Time Regulations limits

Even where overtime is contractual and paid or unpaid, the Working Time Regulations 1998 impose limits. On average you cannot be required to work more than 48 hours a week, normally averaged over 17 weeks, unless you have individually signed an opt-out agreement. You can withdraw an opt-out by giving notice (usually seven days, or up to three months if the agreement specifies). You are also entitled to rest breaks, daily rest of 11 hours and weekly rest. So an employer cannot lawfully require overtime that breaches these limits without a valid opt-out.

Other factors that can make required overtime unlawful

Compulsory overtime can also become unlawful where it operates in a discriminatory way. For example, a rigid requirement to work extra hours could indirectly discriminate against employees with childcare responsibilities or a disability under the Equality Act 2010, in which case the employer would need to justify it as a proportionate means of achieving a legitimate aim, or consider reasonable adjustments or a flexible working request. If overtime demands are so excessive as to risk your health, the employer’s duty of care and health and safety obligations may also be engaged.

What is missing from your question

The answer turns on facts I do not yet have. It would help to know:

1. What your contract or written statement says about hours and overtime, and whether it uses words like “compulsory” or “as required”.
2. Whether you are salaried or paid hourly, and what your effective hourly rate becomes once the extra hours are included.
3. How many total hours you are being asked to work, and whether you have signed a 48-hour opt-out.
4. Whether the requirement affects you differently because of a protected characteristic such as disability or caring responsibilities.

Practical next steps

1. Read your contract and staff handbook carefully to see whether overtime is compulsory and whether it is paid or unpaid.

2. Calculate your effective hourly rate by dividing your total pay by all the hours you actually work in a pay period. If it falls below the National Minimum Wage or National Living Wage, that is a strong basis to challenge the arrangement.

3. Raise it informally with your manager or HR first, in writing, setting out your understanding of your contracted hours and any minimum wage or working time concerns.

4. If informal discussion fails, use your employer’s grievance procedure with a clear written grievance.

5. For minimum wage underpayment you can complain to HMRC, which enforces the National Minimum Wage, or ultimately bring a claim in the employment tribunal for unlawful deduction from wages. Acas early conciliation is a required step before most tribunal claims, and Acas can also advise you free of charge.

6. If the issue is really about the number of hours, consider a statutory flexible working request, which all employees can now make from day one of employment.

If you tell me what your contract actually says and whether you are salaried or hourly paid, I can give you a more precise view on whether the unpaid overtime you are being asked to do is lawful.