Home Advice for Parents & CarersFlexible Working and Working Hours Part time workers – protection against less favourable treatment

Part time workers – protection against less favourable treatment

Last updated: 18 Nov 2021

If you work part time, or want to change from full time to part time hours, the law protects you from less favourable treatment in comparison to your full time colleagues. This article is intended to provide an overview on part time workers’ basic rights under the Part Time Worker Regulations 2000.

If you want information on your right to request to work part time, see our article on flexible working and the right to request.

Who is a part time worker?

There is no set number of hours that makes someone full or part time. A part time worker is anyone who works fewer hours than a full time worker – whatever ‘full time’ means to your employer according to their policy and practice.

The Part Time Worker Regulations apply to both workers and employees from day one of employment – as long as you are working under a contract of employment or for personal services. It makes no difference if you are on a permanent or fixed term contract. However, self-employed workers are not covered.

The right not to be treated less favourably

The Part Time Workers Regulations 2000 were introduced to protect part time workers from less favourable treatment for doing the same or a similar job as full time workers.

If you work fewer than full time hours, you should not be treated less favourably than your full time colleagues. Less favourable treatment could be either in the terms of your contract with your employer (i.e., your pay and benefits), or in how they treat you in the workplace.

For instance, you should not be denied training and career development opportunities offered to full time workers just because you work part-time. Your employer should also not restrict you from other workplace benefits, such as access to car parking, healthcare schemes, gym memberships, or staff discounts.

It is also unlawful for your employer to treat part time workers less favourably by selecting them for redundancy. For more information, see our article on part-time workers and redundancy.

Pro rata principle

The ‘pro rata principle’ must be applied (unless it is inappropriate) to the terms and conditions of your employment.

Pro rata means ‘proportional’ – this means that you should receive the proportion of the pay and benefits the corresponds with how many hours you work compared to a full time worker. For instance, if you work 20 hours per week, and full time workers work 40 hours, you should receive half of the pay and other benefits of a full time worker.

For example:


Part time workers have the right to equal pay, including expenses, bonuses, performance-related pay, and other benefits. This also includes contractual sick leave and pay and statutory entitlements.

Part time workers should be paid the same hourly rate as full time workers doing the same work. If you are salaried, your pay should be pro rata according the number of hours you work. For instance, if you work 4 days a week and full time is 5 days a week, you should receive 4/5th of a full time salary, or 0.8.

Annual leave

Part time workers are entitled to the same holidays as full time worker calculated on a pro rata basis. Employers may not ’round down’ holiday entitlement.

For instance, if you work 4 days a week and full time is 5 days a week, you should receive 4/5ths of the annual leave entitlement that a full time worker receives. If your employer offers the statutory 5.6 weeks (28 days) of paid holiday, you should receive 4/5th of that entitlement (or 0.8). This means you would be entitled to 22.4 days of annual leave.

Your employer must allow you to take 0.4 of a day of annual leave, and cannot round down to 22 days. For instance, if you normally work 8 hours per day, your employer should allow you to take 22 days and 3.2 hours of annual leave.

You can use the government’s holiday entitlement calculator to calculate your annual leave entitlement.

Bank holidays

Normally, bank holidays will either be counted as additional holidays by your employer (you may or may not be paid for them), or deducted from yoru annual leave allowance (so you take the bank holiday as paid holiday).

If full time staff get time off for bank holidays, part time workers who work fixed days each week should be given additional time off where their working pattern does not coincide with bank holidays. For instance, many bank holidays fall either on a Monday. If you don’t work Mondays, your employer should give you additional time off for the bank holiday.

However, if full time staff do not get time off for bank holidays (it is deducted from their annual leave), and work shuts for a bank holiday on a day that you normally work, you will have to use your annual leave for the time off.

For instance, you work one day a week on Monday and you’re entitled to 5.6 days of annual leave a year pro rata. There are 4 bank holidays that fall on a Monday each year, and your work shuts on these days. This means you will need to use 4 days of annual leave, leaving you with only 1.6 days to take a time of your choice. If you work Tuesdays, and there are no bank holidays on Tuesdays, you would have 5.6 days of annual leave to take at a time of your choice.

It is important to keep bank holidays and annual leave in mind when you are negotiating your working pattern with your employer – and check your employment contract / employer leave policy to know how bank holidays will be treated.


Part time workers have the right to join a pension scheme that is provided by the employer and that is open to full time workers, and provide contributions on a pro rata basis reflecting the hours that you work.

Family leave and pay

Part time workers are entitled to the same rights to statutory maternity, paternity and adoption leave and pay. If an employer provides more than the statutory entitlements, they must be calculated on a pro rata basis.


As a part time worker, you are entitled to the same overtime threshold as full time workers (although not necessarily pro rata). If you exceed the threshold for normal full time hours, you may be entitled to overtime. You should check your employment contract for details on overtime thresholds and rates.

Making a comparison to a full time worker

To be able to claim rights under the Part Time Worker Regulations, a part time worker must show that they are being treated less favourably than a full time worker who:

  • Works for the same employer
  • Works under the same type of contract
  • Is engaged in the same or broadly similar work (e.g., similar level of skill, experience and qualification)
  • Works or is based in the same workplace (unless there is no full time work in the same workplace, in which case you can consider a different workplace)

You must be able to point to a real full time worker in the same employment or engaged in broadly similar work, and demonstrate how you are treated less favourably than that worker. For instance, your colleague who does the same or similar job as you who works full time. You cannot compare yourself to a full time worker who is more senior than you, or who do a higher skilled job.

A different type of contract means that if you’re a worker, you can’t compare yourself with someone who is an employee. But if you’re a zero-hours or a fixed-term part-time employee, you can compare yourself to a full time employee. Fixed-term and part-time contracts are not considered to be a different “type” from permanent contracts.  

If you previously worked part time for your employer, but you have received worse terms and conditions after you have moved to part time, you can make the comparison with your previous terms and conditions. This is especially relevant for those returning from maternity and statutory family leave, who may be allowed to return part time but are treated less favourably than they used to be when they worked full time.

When employers can treat part time workers less favourably

An employer might be able justify treating part time workers less favourably if they have a legitimate objective, and the treatment is necessary to achieve the objective and an appropriate way of achieving the objective.

For example, an employer may be able to justify not providing part time workers with health insurance offered to full time workers, because the cost would be disproportionate to the benefit that a part time worker would be entitled to. If it is not possible to give a benefit such as a health insurance plan pro rata, an employer may instead ask a part time worker to make a contribution to the extra cost/benefit.

However, employers must be able to justify the less favourable treatment on each benefit. It is not possible to argue that overall a worker’s terms and conditions are not less favourable, therefore they are not being treated less favourably.

Additional rights under the Equality Act

Part-time workers also have rights under equality law. For example, if part time workers receive less favourable treatment than a full-time employee of the opposite sex, they may have a claim for direct sex discrimination or equal pay. As the majority of part-time workers are women, discrimination against part time workers can also amount to indirect sex discrimination.

There may be some advantages for part time workers to use equality law. Discrimination law is broader in scope than the Part Time Worker Regulations. For example, a worker may be able to claim sex discrimination if an employer does not consider applicants who wish to job share or work part time, or does not allow flexible working. The Part Time Worker Regulations do not apply to job applicants or to requests to work part time.

Under the Equality Act, employers also have no defence to direct discrimination. Part time workers may also be able to make a hypothetical comparison without identifying a real full time worker to compare themselves to. Compensation awards are also likely to be higher for successful discrimination claims.

For more information on the pros and cons, see our blog article on using the Part Time Workers Regulations in litigation.

Frequently asked questions

My employer has offered me part time working, but they say I must take a pay cut

If you are moving from a full time contract to part time hours, you are protected under the Part Time Workers Regulations from less favourable treatment. 

You have a right not to be treated less favourably in the terms of your contract and you should receive no less than the pro-rata the pay you would get as a full time worker.  If your pay cut is more than the pro-rata pay that you would get as a full time worker, then your employer may be treating you less favourably.

For instance, you work full time (5 days per week) and receive £30,000 per year. You request flexible working, and your employer offers to reduce your hours to 3 days per week. You should receive at least 3/5ths or 0.6 of the full time pay for the role, which should be £18,000.

Remember that you should compare your pay to another worker employed by the same employer under the same type of contract and engaged in broadly similar work (similar qualifications, skills and experience) who is working full time. You can also compare your rate of pay with your rate of pay when working full time if you are keeping the same role and just reducing hours. If you are taking a less junior or less well paid role, then you must compare yourself with the lower salary.

I want to return to work part time after maternity, but my employer is offering me an alternative job on less favourable terms. Do I have to accept?

If you use your right to request flexible working after maternity leave, that is to change only your hours, it should not result in a change to the other terms and conditions of your contract. 

However, many employers will refuse a flexible working request and offer alternative jobs on a part time basis to women returning from maternity leave. 

If  you worked full time before your maternity leave and you are returning either to the same job but part time, or a job at the same level but on a part time basis, you may be able to use the Part Time Workers Regulations to argue that you should have no less favourable terms than before.

Under Part Time Worker Regulation 4, a previously full time worker can compare their new terms and conditions with those that they enjoyed immediately before the change. This regulation allows women to compare their part time roles with their previous full time role and argue that they should not be treated less favourably because of their part time status. Any standard change, for instance a pay increase, that have occurred during the period of their absence, must be also applied on your return on a pro-rata basis.  

My employer is making part time workers redundant. Can they do that?

You should not be selected for redundancy (or otherwise be treated less favourably) just because you work part-time, unless your employer can justify this on objective grounds. The justification needs to have a legitimate objective and be necessary and proportionate.

If your employer goes through redundancy, they must put in the selection pool all affected employees. That includes all employees doing the same job – whether or not part-time or full time. The reason for selecting you should not be because you’re working part-time. For more information, see our article on part-time workers and redundancy.

What should I do if I think my employer is treating me less favourably?

Speak to your employer in the first instance and try to resolve things informally. Try to keep communications friendly if you can. It can sometimes be more effective if you focus on solutions and the way forward, rather than the things you are unhappy about. You can say if think you are being treated unfairly because of your part time hours, and explain what you would like your employer to do about it.

Request written reasons

If informal conversations don’t resolve the problem, and you think that you are not being treated fairly, write to your employer requesting a written statement of reasons for less favourable treatment.  You must receive it within 21 days of the request – the law requires your employer to respond within this timeframe.

Raise a grievance

You can also consider raising a grievance. You can find more information in our article on Grievances.

Raising a grievance is important if you think you might later raise a claim in the Employment Tribunal because failure to follow internal resolution methods can disadvantage a claim. 

It is advisable to try and resolve things amicably, as formal processes can damage your relationship with your employer. For some legal insight into grievances and tips on how to engage with your employer before it reaches this point, see our article on Grievances do more harm than good.

Your employer should not ignore your grievance, fail to hear it within a reasonable time or reject it out of hand (as doing so could amount to a breach of your employment contract). However, your employer is not obliged to uphold your complaint.

If you are unhappy with the outcome of your grievance, you should normally be able to appeal it; the procedure will be set out in your employer’s grievance policy. If you are unhappy with the outcome of the appeal process, you can contact us for advice.

Make a claim in the Employment Tribunal

If you are not satisfied with your employer’s stated reasons, or your employer doesn’t respond to give its reasons, you can complain to an employment tribunal within three months of the change of contract.  An Employment Tribunal can make a declaration, order the employer to pay compensation, or recommend that the employer takes further action.

See our section on starting a claim for further information and beware of time limits. You must contact ACAS to start early conciliation within three months less a day of the act complained of (the less favourable treatment).

Tribunal claims can be expensive and long, and there is no guarantee of success, so this step should be considered cautiously. It is often best to try to resolve the issue with your employer. If you are considering bringing a claim, you can contact us for advice.

If you have further questions and would like to contact our advice team please use our advice contact form below or call us.

Advice contact form

The information on the law contained on this site is provided free of charge and does not, and is not intended to, amount to legal advice to any person on a specific case or matter. If you are not a solicitor, you are advised to obtain specific legal advice about your case or matter and not to rely solely on this information. Law and guidance is changing regularly in this area.

We cannot provide advice on employment rights in Northern Ireland as the law is different. You can visit the Labour Relations Agency or call their helpline Workplace Information Service on 03300 555 300.