Part-time workers 


The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (PTWR) define a part-time worker as any worker whose hours are less than those of a full-time worker. This definition covers job shares, workers on zero hours and “short hours” contracts (see above). 


Part-time workers have the right to be treated no less favourably than a comparable full-time worker under the PTWR. This includes the right to the same contractual benefits, such as pay and holiday (normally pro rata to the hours worked), and the right not to be subjected to any other detriment. 


If the reason for the less favourable treatment is unrelated to the worker being part-time, there is no protection (Gibson v The Scottish Ambulance Service [2004] UKEAT 0052/04/1612). Part-time work need not be the only reason for the different treatment, as long as it is the main reason (Carl v University of Sheffield UKEAT/0261/08/CEA).


There is a defence to a claim under the PTWR if an employer can show that its less favourable treatment of part-time workers is justified on objective grounds.


A claim under the PTWR is based on comparison with an equivalent full-time worker, known as the comparator.


Claimants must be able to point to a real life full-time comparator, not a hypothetical one. This is probably the main weakness of the legislation. Care is needed to choose an appropriate comparator. 


The comparator must be “full-time” and it is for the claimant to show that he or she is “full-time”. A recent ruling decided that the PTWR do not protect workers against less favourable treatment than that of other part-time colleagues who are not “full-time” but who work longer hours than they do (The Advocate General for Scotland v Barton [2015] CSIH 92), so where an entire workforce is “part-time”, working different or variable short-hours shifts, the regulations may be of limited help. Under regulation 2(1) PTWR, a worker will be “full-time” if the custom and practice of the employer is to treat their hours as full-time.


As well as being full-time, the comparator must be employed by the same employer under the same type of contract and be doing the same or broadly similar work as the part-time worker bringing the claim. Guidance was given by the Supreme Court in a case brought by the FBU firefighters’ union on behalf of its retained firefighters:


To be a valid comparator, the full-time worker must be employed at the same time as the part-time worker (The Advocate General for Scotland v Barton [2015] CSIH 92). He or she cannot be a former co-worker. 


Part-time workers have the right to the same pension arrangements as full-time workers. Excluding part-time workers from joining an occupational pension scheme is unlawful (Preston v Wolverhampton Healthcare NHS Trust [2004] IRLR 96). Part-time workers will now benefit from pensions auto-enrolment, but only if they earn at least £10,000 a year from one job (see Chapter 4). Separate jobs are not added together, so that someone earning more than £10,000, but from two or more employers, will not be included (although they may be able to join voluntarily). The TUC has pointed out that the £10,000 earnings threshold excludes many part-time workers. 


The European Court of Justice (ECJ) in Steinicke v Bundesanstalt für Arbeit [2003] IRLR 892, held that European law does not prevent pension rights for part-time workers being calculated pro rata, as long as the calculation does not mean that the part-time worker gets proportionately less. However, in Trustees of Uppingham School Retirement Benefits Scheme for Non-Teaching Staff v Shillcock [2002] IRLR 702, the High Court ruled that excluding workers who earned less than the national insurance threshold was justified, even though the outcome was to exclude proportionately more part-time workers.


The protection of part-time workers is based on a European directive — The Part-time Workers Directive — which had to be implemented in UK law by 7 April 2000. In O’Brien v Ministry of Justice [2015] EWCA 1000, Mr O’Brien, a part-time judge who started work in 1975, claimed pension rights from the start of his employment, comparing himself with a full-time judge. Rejecting his claim for pension rights before 7 April 2000, the Court of Appeal confirmed that part-time workers had no right to protection from less favourable treatment during the years of employment before the deadline for implementing the EU Directive in the UK. 


Part-time workers who attend union training should get paid for all the hours on the course (see Chapter 5: Right to time off). However, part-time workers are not necessarily entitled to pay if the course occurs on their days off, that is, on days when they would not have been at work (Calder v Secretary of State for Work and Pensions UKEAT/0512/08/LA).


In relation to overtime pay, it is not contrary to equal treatment laws to pay enhanced rates only when the part-timer has completed the full-time hours (Stadt Lengerich v Helmig [1995] IRLR 216).


However, the ECJ has held that it was unlawful sex discrimination to require a part-time worker to work proportionately more hours than a full-time worker before qualifying for overtime pay:


Part-time workers are not entitled to have account taken of the fact that in earlier years they worked full-time when their redundancy pay is calculated (Barry v Midland Bank [1999] IRLR 581). 


A part-time worker who claims to have received less favourable treatment has the right to ask the employer for a written statement of the reasons for the difference in treatment, and may take a claim of less favourable treatment to an employment tribunal. Less favourable treatment of part-time workers can also amount to indirect sex discrimination or unequal pay if it adversely affects more of one sex than the other (see Chapter 7).


A part-time employee with enough service can make a request to work flexibly (see Chapter 9: Flexible working). For the position on part-time working and bank holidays, see page 124 of Chapter 4.