Many employers are unaware of the new legal requirement for full-time workers, which increased from, four to 4.8 weeks, according to the Forum of Private Business (FPB).
Changes in employment law have confused employers and staff, meaning extra care needs to be taken when calculating holiday in the run-up to Christmas.
Philip Moody, services representative at the FPB, said part-time workers faced the biggest problems as their pro-rata entitlement was difficult to calculate.
He said: “Holiday entitlement has become very complicated as the variations and permutations that have to be taken into account are endless.
“For instance, the calculations for part-time workers and employees working variable hours are very often beyond the ability of many to calculate.”