Urlaubsgeld

Brits tend to use "holiday" instead of "vacation". However, one should avoid using "holiday pay" since that term (also used in the US) means any form of paid time off, such as a government-declared holiday, maternity leave, or sick time off. Since Urlaubsgeld refers only to a discretionary amount paid to the employee for his her vacation or holiday, we would go with "holiday stipend" or "holiday allowance", if your target audience are Brits.