Overtime for Part-Time Workers: What UK Employers Need to Know in 2026

If you offer overtime for part-time workers, it’s essential to treat them equally to your full-time employees. While overtime isn’t a statutory right in the UK, if an employer does offer it, the law requires that part-time workers aren’t treated less favourably when it comes to getting paid for their work. This is covered in the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000. 

As an employer, it’s vital to understand your obligations when it comes to overtime pay for part-time workers. In this guide, we’re going to look at how overtime works for part-time employees, what rates might apply depending on a worker’s contract, how holiday pay works with overtime pay and what you should be checking to ensure your business is compliant. 

What counts as a part-time worker in the UK?

There’s no strict legal threshold for defining when a worker is classed as part-time. In the UK, a part-time worker is defined as someone who regularly works fewer hours than a comparable full-time worker in the same business. For reference, a full-time worker usually works around 35 or more hours a week. If your business only operates for 3 days a week, for example, a full-time worker will naturally work fewer hours, so the definition really depends on each organisation.

This means a part-time worker is defined by the contracts you sign with your employees and what’s usual for your business. The important thing is to keep definitions consistent across your workforce and to treat everyone fairly. 

There’s also a difference between the status of part-time workers and part-time employees. A worker is defined as someone with less structured or a less regular working pattern, or they don’t have guaranteed hours in their contract. An employee has more regular working hours and a more clearly defined role, usually with more responsibility and obligations than a worker. 

Is overtime mandatory for part-time workers?

Overtime isn’t something every business will offer and it’s not a statutory right in UK law. Whether any overtime is compulsory for workers depends on their contract. They only have to do it if contractually required; otherwise it’s voluntary. 

A worker’s contract should also define if any available overtime is guaranteed, or if the employer has the right to stop them from working it if needed. 

Whichever type of overtime is available to workers, taking it comes with certain pay obligations as defined by a worker’s contract.   

There is no statutory overtime rate in UK law. Employers are not legally required to pay more than the National Minimum Wage for overtime hours, unless their employment contract, collective agreement, or company policy says otherwise.

When does overtime kick in for a part-time worker?

The point at which a worker is considered to be doing overtime will usually depend on their contract. This can happen in a couple of different ways: 

Scenario A	Scenario B
Overtime pay kicks in when a worker works over their contracted hours, either with compulsory or voluntary overtime. So a worker on 20 hours per week starts earning overtime at 21 hours, regardless of the full-time hours equivalent. If the same system applies to a full-time worker working over their contracted hours, the part-time worker would receive the same enhanced pay rate.	Overtime pay only kicks in when the part-time worker works over the normal hours of full-time workers. This is the less common approach, but some contracts demand that a part-time worker must work more than the equivalent full-time hours before they receive enhanced pay. Before this threshold, the part-time worker would receive their usual hourly rate.

This is why it’s so important for overtime to be explicitly covered within a worker’s contract. If a part-time worker’s contract doesn’t provide clear rules on overtime pay, it leaves open the possibility for claiming unfavourable treatment. 

Let’s take a look at a working example.

Example: Sarah works 24 hours a week over 3 days. Her full-time colleagues work 37.5 hours. Her contract says overtime applies to all hours above her contracted 24. She works 28 hours in one week, the additional 4 hours are overtime and must be paid at the same enhanced rate that a full-time worker would receive for their first 4 overtime hours.

Overtime pay rates: what does the law say?

Just as there’s no automatic legal right to overtime, there are no specific rates set for overtime pay. National Minimum Wage still applies, so total pay must never fall below this threshold, including any overtime worked. 

The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 also apply here, meaning that overtime rates that apply to full-time workers must apply equally to part-time workers. This could be achieved by simply having a flat overtime rate, or standard rate categories such as time-and-a-half or double-time. These need to be applied fairly and equally to your workforce, regardless of full-time or part-time workers’ status. 

Equal treatment and part-time worker protections

Part-time workers have specific legal protections, as well as general workers’ rights in the UK. Protections for part-time workers are set out in the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000. 

The core aspects of these regulations stipulate that part-time workers cannot be treated less favourably than comparable full-time workers, unless there’s a legitimate and necessary business reason. Under current case law, for a claim of ‘less favourable treatment’ to succeed, the worker’s part-time status must be the sole reason for the difference in treatment, rather than just one of several contributing factors.

Part-time workers should get the same treatment when it comes to: 

• Pay
• Access to overtime and overtime pay
• Holidays
• Pension opportunities 
• Training 
• Promotions

Note for 2026: As of April 2026, the new Fair Work Agency has the authority to inspect payroll records and enforce holiday pay and National Minimum Wage compliance directly. This means businesses no longer just face risks from individual employee tribunals, but also from proactive state enforcement and fines.

National Minimum Wage and overtime

The National Minimum Wage still applies when it comes to overtime pay, meaning a worker’s total pay cannot dip below the National Minimum Wage when overtime is factored in. This normally shouldn’t be a problem if you’re keeping on top of your payroll calculations, but there are a couple of situations where it could be a risk. 

Any unpaid overtime worked could potentially drop an employee’s total pay below the threshold, as could salaried workers being asked to work additional hours beyond their usual contracted hours. These are things your regular payroll checks should cover, especially for workers on variable hours. 

Employers should also be mindful of the April 2026 SSP reforms. Statutory Sick Pay is now payable from the first day of illness (removing ‘waiting days’) and the Lower Earnings Limit has been abolished. This increases the secondary costs of overtime, as any uplift in hours may affect the total sick pay liability for part-time staff.

Holiday pay and overtime: what must be included

What about holiday pay for workers who have access to overtime? Under the Working Time Regulations 1998 and the Employment Rights Act 1996, holiday pay should always reflect ‘normal remuneration’. What this means in practice is that a worker’s holiday pay should be calculated to match their usual pay packet, even if they work part-time or have irregular hours. 

Holiday pay calculations for part-time workers must include any regular overtime worked, using the past year as a guide if possible. Calculate the average hourly rate over the last full 52 weeks worked. For workers with irregular hours or part-year patterns, employers can now choose to use ‘rolled-up’ holiday pay. This allows you to pay an additional 12.07% on top of the hourly rate for overtime worked, provided it is clearly itemised as holiday pay on the payslip.

This must include any type of overtime worked, whether compulsory or voluntary, guaranteed or non-guaranteed. Make sure your payroll includes every type of overtime you offer and always keep the calculations updated to reflect changing hours or shifting work patterns. 

Contractual clauses employers must review

The best method of avoiding admin errors or confusion around overtime pay is to ensure overtime terms are clearly set out in all employment contracts. Here are some key clauses to review to make sure you’re fully compliant and providing clear information: 

• Overtime eligibility – Define who can work overtime and whether it’s voluntary or compulsory.
• Guaranteed overtime – Set out if available overtime is guaranteed or not i.e. can you stop an employee from taking overtime if necessary? 
• Overtime threshold – Is overtime classed as hours worked above contracted hours, or above full-time equivalent hours? 
• Overtime rates – Establish what the overtime pay rates are for everyone, and when each kicks in depending on when or how much overtime is worked. 
• Flexibility clauses – How do flexible or irregular hours impact overtime availability or pay thresholds? 
• Variable hours – Can hours be changed without impacting contractual obligations? 

The important thing is to ensure that contract clauses are clear and understandable. Ambiguous or vague language is a fast route to employment tribunal claims, with so much room for misunderstanding when it comes to overtime and pay calculations. 

Payroll and HR process considerations

For your HR team, keeping on top of workers’ hours is vital. Part-time workers with a variable schedule need to have their worked hours tracked accurately, including any overtime. This is the only way to ensure payroll is using the right information to create accurate payslips for all your workers and correctly calculating holiday pay. 

The easiest way to minimise risk is to use automated HR software that tracks hours and integrates directly with payroll. This helps to eliminate the risk of human error and ensures you’re meeting compliance for every employee, no matter how irregular their hours are. 

Common compliance risks (and how to avoid them)

Most overtime mistakes don’t come from bad intent. They come from contracts that haven’t kept pace with how the business actually operates, or payroll processes built around assumptions that were never written down. Here are the most common pitfalls UK employers run into, and what to do about them.

1. Assuming overtime only applies once a part-time worker exceeds a full-time worker’s hours: This is only the case if an employee’s contract explicitly states it.
2. Paying a different overtime rate to part-time workers than to comparable full-time workers: This would be a direct breach of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000.
3. Excluding regular or voluntary overtime from holiday pay calculations: This is a growing area of tribunal claims, so make sure you’re including every type of overtime pay in your calculations. 
4. Contracts that are silent on the overtime threshold: This creates ambiguity and can increase the risk of disputes, as well as exposing the employer to a less favourable treatment claim. It’s always best to explicitly set out all overtime terms in your employee contracts. 
5. Treating casual or zero-hours workers as exempt from overtime pay rules: The same rules apply if a comparable full-time worker exists, so make sure all your employees are being treated fairly and equitably, no matter their hours or work patterns. 

Best practices for UK employers

Compliance with overtime rules isn’t a one-time fix. It needs to be built into how your contracts are written, how your managers record hours and how your payroll runs every pay period. These are the steps worth prioritising.

1. Create a clear, written overtime policy that defines eligibility, thresholds and rates. Apply it consistently across all part-time and full-time staff..
2. Review employment contracts for all part-time staff and confirm the overtime threshold is explicitly defined.
3. Audit holiday pay calculations to ensure accuracy. If part-time workers regularly work overtime, confirm those hours are included in the 52-week reference period.
4. Train managers on how overtime is approved and recorded, particularly for variable-hours teams.
5. Use integrated HR and payroll software to track hours accurately and reduce the risk of manual errors feeding through to payslips and holiday pay.
6. If contracts are silent or ambiguous, get legal or HR advice before the issue reaches a tribunal.

Stay on top of overtime pay with Employment Hero

Unclear overtime policies are one of the most common triggers for employment tribunal claims in the UK. If your contracts are silent on the overtime threshold, if you’re paying part-time workers at a different rate to comparable full-time staff, or if you’re still excluding overtime from holiday pay calculations, you’re carrying real legal and financial risk.

The good news is that getting it right isn’t complicated if you have the right systems in place. Accurate time and attendance tracking feeds directly into payroll, holiday pay calculates automatically against the correct reference period and your team isn’t manually reconciling hours at the end of every pay run.

That’s exactly what Employment Hero’s AI-powered HR and payroll software is built to do. Time tracking, payroll processing and employee records all run in one platform, so the data your payroll needs is already there. No manual exports, no spreadsheet errors and no gaps in your compliance records.

Want to find out how Employment Hero can support your business?

Disclaimer: The information in this article is current as of April 2026 and has been prepared by Employment Hero UK Ltd and its related bodies corporate (Employment Hero). The views expressed in this article are general information only, are provided in good faith to assist employers and their employees, and should not be relied on as professional advice. Some information is based on data supplied by third parties. While such data is believed to be accurate, it has not been independently verified and no warranties are given that it is complete, accurate, up to date or fit for the purpose for which it is required. Employment Hero does not accept responsibility for any inaccuracy in such data and is not liable for any loss or damages arising directly or indirectly as a result of reliance on, use of or inability to use any information provided in this article. You should undertake your own research and seek professional advice before making any decisions or relying on the information in this article