Four-day weeks – a trial for some?

Written by: Kate Watson
Published on: 14 Jun 2022

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Image: © Stillfx / Adobe Stock

Much has been made in the press about a four-day working week trial, which is due to begin in the UK this summer.

The trial comes amid growing interest from businesses around the world in the potential benefits of giving workers an extra day off. The pilot programme will be run in conjunction with Cambridge and Oxford university academics, alongside Boston College, the UK 4 Day Week Campaign and the think tank Autonomy. It is being overseen by 4 Day Week Global, a campaign group.

Arguably the trial is not revolutionary, as these things have been discussed and tried before. This time, however, it feels more serious.

Evidence from Europe suggests similar trials were hugely successful as they reduced stress, improved morale and boosted productivity over a sustained period. The environmental benefits have been well-documented, too, with marked decreases in the participating countries’ carbon footprints. Workers only have to turn up for four days of hard graft, while still – and here is the thing we’re all excited about – getting paid for five days’ work. And the employers see an increase in productivity.

But if a four-day week, which has been shown in studies across the world to lead to an increase in morale, production and general brilliance among the globe’s workers, is put in place, what are the downsides? Are there any obstacles? Everyone’s a winner, surely?


What very few people seem to be talking about is the impact on those employees who are already working a four-day week for, well, four days’ pay. What about them?

These people are called “part-time workers”. We are familiar with them and have been working with them for some time. They receive 80 per cent of their full-time colleagues’ salaries, precisely because they spend 20 per cent less time at work. Some may work even fewer hours. Where does this all leave them and their employers? Some employers may be far more heavily affected by this aspect of the trial than others. Those with a high proportion of part-time staff may, quite naturally, have a lot of questions.

The Part-time Workers’ Regulations 2000 govern the treatment of part-time staff, and under Regulation 5, a part-time worker has the right not to be treated less favourably than the employer treats a comparable full-time worker, either as regards the terms of their contract, or by being subjected to any other detrimental act or deliberate failure to act by their employer.

This applies where the reason for the less favourable treatment is the fact they work part-time. If, for example, a part-time worker is overlooked for promotion, but the employer can show that the reason was because of performance concerns, this would not amount to less favourable treatment on the ground of part-time status.

Is it justifiable on objective grounds?

The test for whether discrimination has taken place means understanding whether the less favourable treatment is justifiable on objective grounds. What this means, essentially, is whether a reasonable person would take the view that they have been disadvantaged in some way.

When that four-day-a-week (part-time) staff member looks around and sees their colleagues suddenly working the same hours as them for 20 per cent more pay, this is very likely to feel like a disadvantage.

Less favourable treatment cannot be offset by more favourable treatment of a different kind. If, for example, XYZ Ltd decided to offer its existing part-timers a free lunch and an extra day’s holiday to make them feel better, this is not going to offset the disadvantage suffered in the pay packet.

The short answer is employers are going to need to treat their part-time employees fairly and no less favourably than their “full-time” staff. If their full-time staff are now working four days a week and being paid for five days, this will, of course, have a knock-on impact on their existing part-time staff. This is unlikely to be surprising, but it seems very few business leaders are talking about this as the UK moves towards its trial of a shorter working week.

Left behind?

This regime will affect different employers very differently. Some may not feel the impact at all, while others may find it impossible to adopt on cost grounds, particularly where they have a higher-than-average number of part-time workers.

Perhaps radical overhauls of an employer’s IT systems will need to be implemented, or increased staffing to cover those “lost” fifth days. Perhaps they can cover their working hours by putting their staff on varied rotas, so they work different days every week. It could get complex and expensive.

Some employers, particularly in public services such as schools, cannot simply allow staff to go home for a day without putting in place a replacement staff member, or more inventively timetabling their employees’ time.

Employers with a high proportion of part-time staff may feel alarmed or discouraged about this trial, or from considering adopting its principles in future. They may be thinking of reducing their part-timers’ hours still further, in line with the reduction seen by the full-time staff. Or they may be concerned the cost of increasing their current part-time employees’ salaries to match (albeit with any remaining pro-rating applied) those full-timers now entitled to work fewer hours for the same pay will outweigh the benefits they may see and so they give it no further thought.

And what then? Other companies, keen to be seen as the market-leaders or keen to attract the best staff, may drive the changes forward, leaving those employers with higher part-time worker costs struggling to recruit.

The trial is due to last six months and these questions will arise in virtually all businesses taking part. They will need to be answered, and the realities of the cost and management impact must be fully analysed.

Challenges ahead

There are certainly challenges, but this is what trials are for. And it may well be that even where employers are having to foot the bill for an increase in pay for those who currently work part-time, the boost in productivity is sufficient to cover any associated costs with interest. Now that would be a revolution for all.