Holiday accrual calculator (UK)
How much holiday has someone actually built up so far this leave year? The 1⁄12th-a-month sum for new starters and part-timers, minus what they've already taken.
The person
Accrual is 1⁄12 of the annual entitlement per month, rounded up to the nearest half day - the method employers may use in an employee's first year. Time taken beyond accrual isn't unlawful; it's leave in advance, recoverable from final pay only if the contract says so.
Holiday accrues at 1⁄12 of the annual entitlement per month worked, rounded up to the nearest half day. A full-timer on the statutory 28 days accrues 2.33 days a month - 7 days by the end of month three. Subtract what's been taken and you have the balance that matters in a resignation, a request, or a final-pay calculation.
How does holiday accrual work?
UK statutory entitlement is 5.6 weeks a year (capped at 28 days for 5 or more days a week). In an employee's first year, the employer may apply the accrual system: entitlement builds monthly in advance at one twelfth of the annual figure, with part-months rounding the balance up to the nearest half day (gov.uk). After year one the accrual cap falls away and most contracts grant the full year's entitlement at the start of each leave year - but the same monthly arithmetic still decides what a leaver is owed, which is why HR does this sum far more often than once per starter.
Worked example: a starter on 1 June
January-to-December leave year, 5-day week, statutory 28 days. By the end of August they have worked 3 months: 28 × 3⁄12 = 7 days accrued. If they have taken 4, they hold 3. If they ask for a 5-day September holiday, you can grant it as leave in advance (28 × 4⁄12 = 9.33 → 9.5 accrued by end September - the request is within the year's entitlement, just ahead of its accrual). The calculator does exactly this sum for any pattern - and for part-timers the annual figure scales first: 3 days a week = 16.8 days, accruing 1.4 a month.
Accrual month by month: the statutory 28 days
For a 5-day-a-week worker on the statutory minimum, cumulative accrual (1⁄12 a month, rounded up to the half day) runs:
| After month… | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Days accrued | 2.5 | 5 | 7 | 9.5 | 12 | 14 | 16.5 | 19 | 21 | 23.5 | 26 | 28 |
Part-timers scale before rounding: a 3-day week (16.8 days a year) accrues 1.4 a month, so 4.5 days by the end of month three. The calculator above does any pattern.
The three traps
- Accrual during absence. Statutory holiday keeps accruing through sickness and family leave - the entitlement never pauses, only the work does. Long-term absence returns with a stack of accrued leave attached (the sick-leave accrual rules).
- Rounding down. Balances round up to the half day; rounding down below the statutory figure is not permitted. A spreadsheet that truncates 9.33 to 9 is quietly unlawful once a year per person.
- Taken-ahead leavers. Someone who leaves having taken more than they accrued owes the difference - but you can only deduct it from final pay if the contract says so in terms. If yours doesn't, fix the contract, not the payslip.
Frequently asked questions
How does holiday accrue in the first year of employment?
In the first year an employer may use the accrual system: leave builds up monthly in advance at one twelfth of the annual entitlement, rounded up to the nearest half day. After the first year, most contracts give the full annual entitlement from the start of each leave year.
How much holiday does someone accrue per month?
One twelfth of their annual entitlement. A full-timer on the 28-day statutory minimum accrues 2.33 days a month - so roughly 7 days after three months, rounded up to the nearest half day. Someone on a company allowance accrues one twelfth of that allowance instead.
Can an employee take holiday they haven't accrued yet?
Yes, if the employer agrees - the accrual system is a ceiling employers may apply in the first year, not a ban on advancing leave. If someone leaves having taken more than they accrued, the excess can only be recovered from final pay if the contract allows it.
Does holiday accrue during sick leave and parental leave?
Yes. Statutory holiday keeps accruing during sickness absence and family leave such as maternity - absence pauses the work, not the entitlement. This regularly surprises employers with long-term absentees returning to a stack of accrued leave.
Worth reading alongside
This calculator applies the statutory rules as published and shows its working, but it cannot know your contracts, your policies or anything unusual about the case. Treat the figure as a starting point, and take advice on anything contested or expensive.
Balances that keep themselves
CoDash accrues every person's entitlement from their working pattern and start date automatically - starters, part-timers, carry-over and half days included - and the balance an employee sees always agrees with the one HR sees.