What is pro rata holiday and how do you calculate it?

How to Calculate Pro-Rata Holiday Entitlement (UK Guide)

Working out holiday entitlement fairly and accurately can be confusing, especially when dealing with part-time workers, new starters, or leavers. But understanding pro-rata holiday entitlement is crucial for legal compliance and employee satisfaction.

In this guide, we’ll break down what pro-rata holiday means, how to calculate it, and why it matters in the workplace. This is especially relevant for UK employers managing diverse working patterns and navigating ever-changing employment regulations.

What Does Pro-Rata Holiday Mean?

The term pro rata comes from Latin and means “in proportion.” In the context of annual leave, it refers to calculating holiday entitlement fairly based on the amount of time someone works.

This means that part-time employees, or those who start or leave partway through the holiday year, receive a proportionate amount of annual leave compared to full-time or full-year employees. In other words, everyone gets the same rate of holiday, adjusted to match how much of the year they work.

How much annual leave do I need to give?

In the UK, the minimum statutory amount of annual leave is 5.6 weeks, which is the equivalent of 28 days for full-time employees. The 5.6 weeks can include bank/ public holidays at the employer’s discretion. However, your starting point is the contract of employment which will set out the amount due as there may be an agreement to a higher contractual entitlement.

Valid reasons for making pro rata adjustments to annual leave entitlement:

• • Part-time hours: pro-rata their annual leave to an entitlement which is proportionate to a full-time person in your organisation. 
  • Mid-year starter: adjust the entitlement based on how much of the leave year remains as at the start date of employment.
  • Mid-year leaver:  adjust the entitlement based on the amount of the leave year served.
  • Mid-year change to contractual hours:  the total entitlement for the year should be adjusted by weighting the amount of the year spent at each level of entitlement.

Why is it essential to pro rata holiday for part-time employees?

Part-time employees are protected under the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000 from being treated less favourably on the grounds of their part-time status.  Therefore, getting the calculations right is key to ensuring that legal obligations are met, complaints are prevented, and your employer brand is protected.

How Do I Pro-Rata Annual Leave for Part-Time Employees?

Annual leave must always be pro-rated fairly for part-time staff. The method you use depends on whether your business tracks holiday in hours or days. If the working pattern is irregular or involves different shift lengths, managing entitlement in hours is usually more accurate.

Example: Reducing from 37.5 hours (5 days) to 20 hours (4 days)

Scenario:

• Full-time = 37.5 hours per week (5 days)

• Full-time entitlement = 28 days (5.6 weeks)

• Employee moves to 20 hours per week (4 days)

What about if my employee condenses their full-time hours into four days rather than five days? Do I pro-rata their leave?

This will depend on whether you calculate your annual leave in days or hours.

If days, then yes, as if they wanted to book a week off work, they would only need to take four days rather than five.

If hours, then no, as their new working day will be longer and the amount of time they would book off for one day would be longer. 

What happens if my employee changes their hours part-way through the annual leave year?

In this case, you will need to do a further pro-rata calculation by calculating the proportions of the year in which both entitlements will have accrued. 

For example, if someone changes their hours exactly halfway through the year, you would pro-rata the initial amount of annual leave by six months and then the adjusted annual leave amount by six months and add them together.