Quick Answer: Part-Time Holiday Entitlement Formula
Annual leave = 5.6 x days worked per week
A part-time worker on 3 days per week receives 3 x 5.6 = 16.8 days of statutory annual leave. This is the legal minimum under the Working Time Regulations 1998 and the Part-Time Workers Regulations 2000.
The Legal Basis
Under the Working Time Regulations 1998, all workers are entitled to 5.6 weeks of paid annual leave. The Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 ensures part-time workers receive this on a pro-rata basis.
Pro-Rata Calculation Table
| Days Per Week | Calculation | Statutory 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 |
The statutory cap is 28 days. Workers on 6 days per week receive 28 days, not 33.6.
Handling Fractions
When calculations produce fractions (like 16.8 days), employers cannot round down. ACAS recommends rounding up in the employee's favour. Alternatively, allow partial day leave.
Bank Holidays and Part-Time Workers
This is the area where most employer errors occur. There is no automatic right to bank holidays off -- it depends entirely on the employment contract.
Approach 1: Bank Holidays Included in 5.6 Weeks
The statutory 5.6 weeks includes bank holidays. Part-time workers take bank holidays that fall on their normal working days and deduct them from their total.
Problem: A worker who works Monday to Wednesday benefits from more bank holidays (most fall on Mondays) than someone working Thursday to Saturday. This can amount to less favourable treatment.
Solution: Calculate each worker's total entitlement including their pro-rata share of bank holidays, and adjust so everyone receives equivalent total time off.
Approach 2: Bank Holidays on Top of 5.6 Weeks
If full-time staff get 28 days plus 8 bank holidays (36 days total), part-time workers must receive a pro-rata share of the total.
Formula: (Total full-time days / full-time working days) x part-time working days
Example: Full-time = 36 days. Part-time on 3 days: (36 / 5) x 3 = 21.6 days total. Subtract bank holidays falling on their working days.
Irregular Hours Workers (Since January 2024)
The Working Time Regulations were amended in January 2024 to introduce specific rules for irregular hours workers and part-year workers.
Who Qualifies as an Irregular Hours Worker?
A worker is an irregular hours worker if the number of paid hours they work in each pay period during the term of their contract is wholly or mostly variable.
The 12.07% Accrual Method
For irregular hours workers, holiday accrues at 12.07% of hours worked in each pay period.
Example: A zero-hours worker works 80 hours in January. Holiday accrued = 80 x 0.1207 = 9.66 hours.
Rolled-Up Holiday Pay
Since January 2024, employers can lawfully use rolled-up holiday pay for irregular hours and part-year workers. This adds a 12.07% uplift to each payment.
Requirements:
- Must be clearly shown as a separate line on the payslip
- Calculated on total earnings including overtime and commission
- Applied consistently across all qualifying workers
Changing Working Patterns Mid-Year
When an employee changes hours (e.g. from 3 to 4 days per week), their remaining entitlement must be recalculated.
Step 1: Calculate leave used so far under the old pattern Step 2: Calculate remaining entitlement under the new pattern for the rest of the year Step 3: Subtract leave already taken from the combined total
Example: An employee works 3 days/week (16.8 days entitlement) and has taken 8 days in the first 6 months. They move to 4 days/week from 1 July.
- Remaining entitlement at new rate: (22.4 / 2) = 11.2 days for second half
- Total for the year: 8.4 (first half) + 11.2 (second half) = 19.6 days
- Already taken: 8 days
- Remaining: 11.6 days
Common Employer Mistakes
Mistake 1: Giving Part-Time Workers Fewer Bank Holidays Pro-Rata
If full-time workers get 8 bank holidays on top of 20 days, part-time workers on 3 days must get a pro-rata share of the combined 36 days (21.6 total), not just 3/5 of 20 days (12) plus whatever bank holidays happen to fall on their working days.
Mistake 2: Rounding Down Fractional Entitlements
Rounding 16.8 down to 16 is unlawful. Always round up or allow fractional days.
Mistake 3: Forgetting Accrual During Absence
Holiday accrues during maternity leave, paternity leave, adoption leave, and sick leave. A part-time worker returning from 6 months' maternity leave has accrued 8.4 days (for 3-day worker) that must be available.
Mistake 4: Not Adjusting When Patterns Change
Failing to recalculate when an employee changes from part-time to full-time (or vice versa) leads to over- or under-entitlement.
Practical Tools and Checklists
Annual Audit Checklist
- Verify all part-time employees' working patterns are recorded accurately
- Check pro-rata calculations match statutory minimums
- Confirm bank holiday arrangements are non-discriminatory
- Review irregular hours workers' accrual method
- Ensure carry-over rules apply equally to part-time and full-time staff
- Check that holiday accrual during absence is being tracked
- Verify holiday pay includes regular overtime and commission (for first 4 weeks)
How Grove HR Handles Part-Time Entitlements
Grove HR automates all part-time holiday calculations:
- Automatic pro-rata based on each employee's working pattern
- Bank holiday management that ensures non-discriminatory treatment
- Mid-year pattern changes recalculated automatically
- Irregular hours accrual using the 12.07% method
- Rolled-up holiday pay tracking where used
Start managing part-time leave properly with Grove HR.
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The Grove Team
Grove HR
The Grove Team writes about HR best practices, compliance, and workplace culture for Grove. Helping UK businesses cultivate thriving teams.
