Part time workers – the legal background

Aug 3, 2020 | Terms and Conditions

Flexibility in working practices and working hours has increased, particularly very recently with many employers being perhaps forced into accepting reduced hours from workers unable to work full time as a result of Coronavirus. It’s perhaps a good opportunity therefore to consider what the legal issues regarding part time working are.

There is legislation regulating part time working specifying that it is unlawful to treat part time workers less favourably than a comparable full time worker (unless the treatment can be objectively justified). But what does this actually mean in practice?

Who is protected?

The first thing to note is that, unlike some employment rights, this protection doesn’t just apply to employees, it applies to workers as well. A worker in your business might be a casual member of staff coming in on an ad hoc/occasional/seasonal basis.

Who are they compared with?

Part time employees or workers are protected from less favourable treatment than ‘comparable’ full time workers. A comparable full time worker would be someone under the same type of contract, doing the same or similar work, with similar qualifications/skills/experience, and usually working in the same place. So although casual workers are protected, their comparator would not normally be a full time employed person.

When is less favourable treatment justified?

If there is objective justification for less favourable treatment, this would not be unlawful. To satisfy the objective justification test, you would need to demonstrate that the less favourable treatment is necessary to achieve a legitimate business aim, and is an appropriate means of achieving that aim.

This is most likely to apply to the allocation of some benefits which cannot be pro-rated, like healthcare.

Pay and conditions

The protection against less favourable treatment means that part time workers should have no less favourable terms and conditions and pay arrangements than their full time colleagues. This is qualified by the pro rata principle, meaning that part time workers’ pay and benefits should be the appropriate proportion of a full time worker’s based on the number of hours they work.

Other relevant considerations

This protection doesn’t just extend to pay and conditions. There are other aspects of work in respect of which you need to consider the treatment of part time workers and the impact of decisions you make.

For example, you cannot select a worker for redundancy because of their part time status unless this can be objectively justified, and any criteria you are applying for redundancy selection such as number of sales made or similar, must be pro rated for part time workers.


Part time workers must have equal access to things like sabbaticals, promotion opportunities and training. This means that unless it can be objectively justified, you can’t refuse to promote a worker because of their part time status.

Training and other learning and development opportunities must be accessible to part time workers, which means for example that consideration needs to be given to making sure that training doesn’t only take place on days your part time workers are not available.

In order to avoid legal challenge, you should consider when making decisions, whether part time workers are adversely impacted; whether if that is the case, that can be changed; and if not, whether there is a legitimate business objective being met.

Documenting the fact that you have considered the impact of what you are doing on part time workers and can justify whatever decision has been made will be helpful in avoiding a legal claim later, as you will be able to make your reasons clear to affected workers and show that either they have not been treated less favourably, or that it is necessary.


If you are wondering about whether something you have in place or are planning to put in place in your business might have legal implications in respect of part time workers, do get in touch for advice.