Holiday accrual

Holiday starts building from the start

Statutory annual leave begins to accrue when employment starts. Contractual leave above the statutory minimum follows the employer's terms, so keep the two parts distinguishable if different rules apply.

Accrual matters most when someone starts or leaves part-way through a leave year, changes hours or has an irregular working arrangement. First establish the leave year, employment dates and working pattern. Then use the method that fits that worker. The GOV.UK leave-entitlement guidance routes employers to the relevant calculation.

Changes need a dated calculation

When hours change, split the record at the effective date. Calculate what built up under the old pattern, what was taken and what builds under the new one. Do not overwrite the earlier pattern and recalculate the whole year as though it had always applied.

Holiday can continue to accrue during periods such as sickness absence and statutory family leave. Accrual is not the same as carry-over: one builds entitlement during the current leave year, while the other moves unused entitlement into a later year.

Worker type can change the method

Great Britain has specific current rules for qualifying irregular-hours and part-year workers. Northern Ireland does not use that same post-2024 regime. A casual label, a varying rota or the phrase “pro rata” is not enough to select a formula.

HollyHR's calculator can help with documented regular weekly patterns, including starters and leavers. It does not calculate entitlement for irregular-hours or part-year workers.