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An employer's guide to part-time workers' rights

Part-time workers are protected by the Part-Time Workers (Protection from less favourable Treatment) Regulations 2000 (the Regulations). These rules protect part-time workers from less favourable treatment than their full-time colleagues, unless such treatment can be justified on objective grounds.

The Part-Time Workers (Protection from less favourable Treatment) Regulations 2000

It should be noted that the Regulations have wide applicability as they relate to workers rather than just employees.

What are the Part-Time Workers Regulations?

The Regulations define both full-time and part-time workers.

  • A part-time worker is a person who is paid wholly or partly by reference to the time they work and is not identifiable as a full-time worker having regard to the employer’s custom and practice in relation to workers employed under the same type of contract.
  • A full-time worker is a person who is paid wholly or partly by reference to the time they work and who is identifiable as a full-time worker having regard to the employer’s custom and practice.


In order to bring a claim under the Part-Time Workers Regulations, the worker must identify a comparator. This must be someone:

  • employed by the same employer;
  • employed on the same type of contract;
  • engaged in the same or broadly similar work as the worker, having regard to, where relevant, whether they have similar levels of experience, qualifications and skills;
  • who works or is based in the same place or establishment as the worker or, where there is no comparator fulfilling the three above requirements, someone who works or is based at a different establishment and satisfies those criteria.

Unlike some discrimination legislation, there is no scope to base a claim on a hypothetical comparator. However, if an actual comparator has been identified, it is open to a tribunal to also consider hypothetical comparators in addressing the question as to why the employer treated the worker less favourably.


For the purpose of identifying a comparator, the Regulations set out four categories of worker:

  • employees employed under a contract of employment which is not a contract of apprenticeship;
  • employees under a contract of apprenticeship;
  • workers who are not employees; or
  • any other description of worker that it is reasonable for the employer to treat differently from other workers on the ground that workers of that description have a different type of contract.

Same or Broadly Similar Work

In considering whether a part timer is employed on the same or broadly similar work, case law has held that it is a matter of looking at whether the main duties and responsibilities between the two groups were the same. “The question then is whether any differences are of such importance as to prevent their work overall from being regarded the same or broadly similar.”

The emphasis should be on the similarities between the jobs and their importance to the employer. Where there are differences, the question is whether they are significant enough to prevent the work overall being considered the same or broadly similar.

Changing from full-time to part-time employment

Following a switch from a full-time to a part-time contract, the worker can compare their new terms and conditions with those they were engaged on before the change. A claim can be brought if the worker can point to less favourable treatment. Strictly speaking, the comparator in these circumstances is a hypothetical one and this is an exception to the general rule that there cannot be a hypothetical comparator.

Less Favourable Treatment

A part-time worker has the right not to be treated less favourably than a full-time comparator:

  • in relation to the terms of their contract;
  • by being subject to any other detriment by an act, or a deliberate failure to act, by their employer.

This applies where the difference of treatment is because of the worker’s status as a part-time worker and the differences cannot be objectively justified. For instance, the failure to promote a part-time worker because of concerns about performance would be defendable if it can be clearly demonstrated that the failure to promote was not because of the worker’s part-time status, but rather their performance in the job.

There are four questions to ask in considering whether there has been less favourable treatment:

  • What is the treatment complained of?
  • Is the treatment less favourable than that of a full-time comparator?
  • Is the less favourable treatment on the grounds that the worker is a part-time worker?
  • If so, is it justified on objective grounds?

How part-time workers are protected against less favourable treatment

These concepts are taken from the Equality Act 2010. The tribunal is required to ask itself whether a reasonable person would take the view that the worker had been disadvantaged in some way. Therefore, less favourable treatment or detriment cannot be 'off-set' or 'cancelled-out' by more favourable treatment of a different kind. Unlike the Fixed-Term Worker Regulations, there is no scope for the tribunal to look at the contract as a whole; it must be considered on a 'term-by-term' basis.

The less favourable treatment must be because of the worker’s part-time status. The burden of proof is on the employer to demonstrate that the less favourable treatment was for a reason unconnected with part-time status.

Pro Rata Principle

Regulation 5 states that, in determining whether a worker has been unfavourably treated, the pro rata principle should apply unless it is inappropriate in the circumstances. For example, if a full-time worker working a five day week receives 25 days’ annual holiday a part-time worker working a three day week should receive 15 days’ holiday.

Not all benefits are easily capable of being pro-rated, in which case, the employer will need to find a suitable alternative. For example, if company cars are provided to full-time employees, a part-timer might be given a less expensive car or a cash allowance in lieu.

Can part-time employees work overtime?

Regulation 5 lays down that a part-time worker will only qualify for a premium over-time pay rate once the worker has worked the same number of hours that a full-time worker is required to work to qualify for a premium rate over-time payment. For example, if full-time workers work a 40 hour week before receiving premium rate overtime, then where a part-time worker who usually works a 20 hour week works a 40 hour week, they will receive their normal pay for the additional 20 hours but won’t receive the premium over-time payment until they have completed 40 hours.

Public and Bank Holiday entitlement for part-time workers

Ordinary contractual holiday will be pro-rated as shown above. However, bank or public holidays can be more problematic. Part-time workers who do not work on Mondays will miss several public holidays and may feel they are suffering a detriment. However, historically, many employers have taken the view that if a worker does not ordinarily work on a bank holiday, they are not entitled to paid time off. There are two approaches an organisation can take:

  1. Pro-rata the holiday. Simply divide the number of public holidays by the proportion of the week worked and allow holidays on that basis, even if the worker concerned does not work on some of the bank holidays. This is the safer approach as it stays within the spirit of the Regulations; or
  2. Only allow a public holiday if the worker happens to work on the day the holiday falls. Part-time workers who do not work Mondays will suffer disproportionately, while workers who do work on Mondays are likely to benefit by receiving a disproportionately high number of holidays.

If an employer chooses the latter approach, they may be able to defend it on the basis:

  • That the reason for the less favourable treatment is not the worker’s part-time status; or
  • That the less favourable treatment can be objectively justified.

There have been no reported cases on this justification defence. However, a recent case on the 'reason' defence (McMenemy v Capita Business Services (2007)) supported the argument that the reason for not giving the holiday was merely because the employee was not working on the day the holiday fell, and not because he was a part-time worker.

On the facts of this case, all employees were required to work on a flexible roster and could work any day of the week, including Mondays. Therefore, some full-time workers might not work on a bank holiday if they were not rostered to do so, and would lose the holiday accordingly. The tribunal accepted that part-time workers would be disproportionately affected by this approach, but, as the Regulations do not include indirect discrimination provisions, the claim failed. Employers who operate on a more conventional Monday to Friday working week may find it less easy to avoid findings of less favourable treatment as they will not be able to point to full-time workers who are also disadvantaged by the policy. These employers will have to look to an objective justification defence (see below).

Objective justification

An employer may be able to defend less favourable treatment on the grounds that it can be objectively justified (Regulation 5). To do so the employer must show:

  • That the objective justification corresponds to a real need on the part of the business;
  • It is an appropriate means of achieving the objective; and
  • It is necessary to achieve the objective.

An objective balance must be struck between the discriminatory effects of the provision and the reasonable needs of the employer, (the principle of proportionality). The employer does not have to show that the measure in question is the only way of achieving the desired objective but, if the part-time worker can point to another, non-discriminatory way in which the employer could have achieved the same aim, there is risk that a tribunal will find that the defence of objective justification has not been made out.

Factors which are commonly relied on by employers to justify a difference in treatment between full-time and part-time workers include: skills, qualifications, experience, market forces and geographical differences. Tribunals are increasingly unwilling to accept arguments based on cost and resources and it is not enough for employers to make generalisations to the effect that part-time workers are less committed or take longer than full-time workers to acquire the necessary skills and experience.

BIS guidance on equal treatment for part-time workers

Guidance (now archived) from BIS usefully identified a number of areas in which employers must ensure equality of treatment for part-time workers, on a pro-rata basis where appropriate:

  • Part-time workers should receive the same hourly rate as comparable full-time workers.
  • Part-time workers should receive the same hourly rate of overtime pay as comparable full-time workers once they have worked more than the normal full-time hours.
  • In the reorganisation of workloads, part-time workers should not be treated less favourably than full-time workers unless this treatment can be objectively justified.
  • Previous or current part-time status should not of itself be a barrier to promotion to a post, whether that post is full-time or part-time.
  • Part-time workers should be able to participate on a pro-rata basis in profit-sharing or share option schemes available to full-time staff, unless there are objective grounds for excluding them.
  • Part-time workers should not be treated less favourably than full-time workers in terms of calculating the rate of sick pay or maternity pay, the length of service required to qualify for payment or the length of time for which the payment is received.
  • Employers should not discriminate between full-time and part-time workers in relation to access to pension schemes, unless different treatment is justified on objective grounds.
  • Employers should not exclude part-time staff from training simply because they work part-time.
  • The criteria used to select jobs for redundancy should be objectively justified and part-time workers must not be treated less favourably than comparable full-time workers.
  • Benefits such as subsidised mortgages and staff discounts should be applied to part-time workers, unless an exception is justified on objective grounds.
  • Where a benefit, such as health insurance or company cars, cannot be applied pro-rata, this is not of itself an objective justification for denying it to part-time workers. However, the disproportionate cost to the organisation might amount to objective justification.
  • The holiday entitlement of part-time staff should be pro-rata to that of full-time workers.
  • Contractual or enhanced maternity leave and parental leave should be available to part-time workers as well as full-time workers.
  • Career break schemes should be available to part-time workers in the same way as for full-time workers, unless their exclusion is objectively justified on grounds other than their part-time status.

Abbreviated government guidance on part-time workers' rights is available online.

Right to request part-time working

There is no right to request part-time working arrangements under the Regulations. However, there is the separate statutory right to request flexible working for all employees with at least 26 weeks continuous service [Flexible working guide].

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