The Legal Basis
Under the Working Time Regulations 1998, all workers in the UK are entitled to a minimum of 5.6 weeks of paid annual leave per year. The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 ensures this right applies equally to part-time workers on a pro-rata basis.
The Basic Calculation
The formula for part-time holiday entitlement is straightforward:
Annual leave = 5.6 x days worked per week
| Days Per Week | Calculation | Annual Leave Entitlement |
|---|---|---|
| 5 (full-time) | 5.6 x 5 | 28 days |
| 4 | 5.6 x 4 | 22.4 days |
| 3 | 5.6 x 3 | 16.8 days |
| 2.5 | 5.6 x 2.5 | 14 days |
| 2 | 5.6 x 2 | 11.2 days |
| 1 | 5.6 x 1 | 5.6 days |
Note: The statutory maximum is capped at 28 days, even if the calculation would produce a higher number (for example, someone working 6 days per week would still receive 28 days, not 33.6).
Handling Fractions of Days
When the calculation produces a fraction (such as 16.8 days), employers cannot round down. They can either:
- Round up to the nearest half or whole day (e.g. 16.8 becomes 17 days)
- Allow the fractional day to be taken as a partial day off
ACAS recommends rounding up in the employee's favour.
Bank Holidays and Part-Time Workers
This is where many employers make mistakes. There is no automatic right to take bank holidays off. Employers have two common approaches:
Approach 1: Bank Holidays Included
The 5.6 weeks includes bank holidays. Part-time workers take bank holidays that fall on their working days and deduct them from their total entitlement.
Approach 2: Bank Holidays on Top
The employer gives bank holidays in addition to the statutory 5.6 weeks. Part-time workers should receive a pro-rata share of the bank holiday allowance to avoid less favourable treatment.
Example: If full-time workers get 28 days plus 8 bank holidays (36 total), a 3-day worker should get: (36 / 5) x 3 = 21.6 days total, minus any bank holidays that fall on their working days.
Irregular Hours and Annualised Calculations
For workers whose hours vary from week to week, use the hours-based method:
- Calculate the total hours worked per year
- Divide by 46.4 (52 weeks minus 5.6 weeks of leave)
- The result is the number of hours of leave per week
- Multiply by 5.6 to get total hours of annual leave
Alternatively, use the 12.07% method: for every hour worked, 0.1207 hours of holiday accrues.
Accrual for New Starters
Part-time workers who join mid-year accrue leave on a pro-rata basis from their start date. Calculate the proportion of the holiday year remaining and apply it to their full annual entitlement.
Example: A 3-day worker (16.8 days entitlement) starts on 1 July with a January-December holiday year. They have 6 months remaining = 16.8 x (6/12) = 8.4 days for that year.
Common Mistakes to Avoid
- Giving part-time workers fewer bank holidays pro-rata than full-time colleagues
- Rounding down fractional entitlements
- Forgetting to adjust when an employee changes their working pattern mid-year
- Not accruing leave during maternity, paternity, or sick leave
How Grove HR Automates This
Grove HR calculates part-time entitlements automatically based on each employee's working pattern. When patterns change, entitlements adjust mid-year. The system handles bank holiday pro-rata, accrual for new starters, and carry-over rules without manual spreadsheet work.
Frequently Asked Questions
Can an employer include bank holidays in the 5.6 weeks?
Yes. There is no legal right to bank holidays off in addition to the 5.6 weeks of statutory leave. Employers can include bank holidays within the 28-day minimum. However, part-time workers must not be treated less favourably than full-time colleagues.
What if a part-time worker changes their hours mid-year?
When a worker changes from, say, 3 days to 4 days per week, their remaining entitlement for the year should be recalculated pro rata from the date of the change. Any leave already taken is deducted from the recalculated total.
Do part-time workers accrue holiday during sick leave?
Yes. Holiday continues to accrue during periods of sick leave, including long-term sickness. The worker can take their accrued holiday at a later date or, if still sick at year end, carry it over.