Reviewing part-time worker policies after Data Cars

Many employers assume that treating everyone the same means treating everyone fairly. The Supreme Court’s decision in Augustine v Data Cars Ltd [2026] UKSC 30 highlights the limitations of that assumption.

The Court held that a part-time worker does not need to show that working part-time was the sole reason for less favourable treatment. It is enough that it was an effective or significant cause of the disadvantage.

The decision strengthens protections for part-time workers and should prompt employers to review policies, benefits and pay arrangements that may disproportionately affect employees who work fewer hours.

The facts

Warren Augustine worked as a private hire driver for Data Cars Ltd. All drivers, whether part-time or full-time, were charged a fixed weekly “circuit fee” to access the company’s booking system. The fee applied regardless of the number of hours worked.

Mr Augustine argued that this resulted in him paying a higher fee per hour worked than comparable full-time drivers. Although every driver paid the same amount, the charge consumed a greater proportion of a part-time driver’s earnings and left him taking home less pay per hour than a full-time comparator.

The key legal issue was whether the less favourable treatment had to be solely because he was a part-time worker. Earlier authority suggested it did. The Supreme Court disagreed.

The Supreme Court’s decision

The Court unanimously allowed the appeal. It held that regulation 5 of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 does not require part-time status to be the sole cause of less favourable treatment. Instead, it need only be an effective or substantial cause.

The Court recognised that workplace decisions are often influenced by several factors. The presence of other commercial, operational, or administrative reasons does not prevent part-time working from being an effective cause of a disadvantage.

In doing so, the Court rejected a restrictive approach that had been applied for many years and confirmed that the Regulations provide broader protection than previously understood.

What does this mean in practice for employers?

At first glance, Data Cars’ approach appeared fair because every driver paid the same fee. The judgment shows why that is not always enough.

Following Data Cars, employers should look beyond whether a policy is applied consistently and consider whether it has a disproportionate impact on part-time workers. This is particularly important as flexible and part-time working arrangements become more common.

A sensible starting point is to review arrangements based on fixed amounts, minimum thresholds, or assumptions about full-time working, including:

• fixed fees, deductions or employee contributions;
• bonus and commission thresholds;
• attendance-related incentives;
• qualifying periods for benefits;
• allowances and expense arrangements;
• access to training and development opportunities; and
• benefits that are not provided on a pro rata basis.

A common example might be a bonus scheme that requires employees to work a minimum number of hours, or achieve a minimum level of output, before becoming eligible for a payment. Although the rule applies equally to all employees, it may place part-time workers at a particular disadvantage and therefore require objective justification.

The Regulations generally require part-time workers to receive pay and benefits on a proportionate basis compared with comparable full-time workers, unless different treatment can be objectively justified. Protection extends beyond pay and can cover contractual benefits, sick pay, annual leave, pension arrangements and training opportunities. Policies that appear neutral on their face may therefore create legal risk if they place a greater burden on employees who work fewer hours.

Can these arrangements still be justified?

The decision does not mean that every difference in treatment will be unlawful. A worker must still identify an appropriate comparator and establish that their part-time status was an effective cause of the disadvantage. However, Data Cars makes clear that employers should not confuse causation with justification.

The existence of a commercial, operational, or administrative reason for a policy does not necessarily break the link between the disadvantage and part-time working. If part-time status is an effective cause of the treatment, the Regulations may apply.

That does not mean legitimate business reasons are irrelevant. Employers may still be able to defend a policy if they can demonstrate that it pursues a legitimate objective and that the means used to achieve that objective are proportionate.

In practice, objective justification can be difficult to establish. Employers will need evidence demonstrating not only why the policy serves a legitimate business aim, but also why the particular approach adopted is necessary and why a less disadvantageous alternative would not achieve the same objective.

Employers should therefore be prepared to explain not only why a particular arrangement exists, but also why it remains appropriate and whether less disadvantageous alternatives have been considered. Keeping a record of the rationale behind policies, and reviewing them periodically, can help reduce risk if a challenge arises.

Looking ahead

The broader significance of Data Cars extends far beyond the private hire sector. Policies developed around traditional full-time working patterns are now more likely to come under scrutiny.

For many employers, the greatest risk will not come from an obviously discriminatory policy, but from a long-standing arrangement that nobody has questioned because it applies equally to everyone. The Supreme Court’s message is clear: consistency alone is not enough. Employers should look beyond whether a policy is uniformly applied and consider whether its practical effect is fair, proportionate and capable of justification.

Employers should review existing policies now to identify arrangements that may unintentionally disadvantage part-time workers. If you would like assistance auditing your policies, assessing legal risk, or considering whether particular arrangements can be objectively justified, please contact Employment Partner Marie van der Zyl OBE.