Operators have been urged to ensure they are calculating holiday pay correctly.
The warning comes after Eddie Stobart agreed to pay £364,000 to more than 430 drivers who had not received the rate they were entitled to.
Union Unite claimed the haulier had not taken into account allowances and overtime that would have contributed to a higher rate of average holiday pay when calculating what drivers should receive.
It said it was paying drivers only their basic pay and a daily supplement for the 20 days holiday required under the Working Time Directive.
Eddie Stobart agreed to compensate 439 drivers in an out-of-court settlement following a five-year dispute between the union and the haulier. They will each receive a pay-out of up to £1,000.
Rafia Ahmad, employment solicitor at Backhouse Jones, warned operators to make sure they take bonuses and allowances into account when calculating how much holiday pay drivers are owed.
“When it comes to holiday pay they have to look at the average amount earned over a period of time, say 20 days. That is usually above basic pay,” she said.
In a separate case in 2014, brought against road maintenance firm Bear Scotland, the Employment Appeals Tribunal ruled that holiday pay calculations should take into account certain additional payments such as commission and overtime.
Adrian Jones, Unite regional officer for road transport, said the union was pleased that its dispute with Eddie Stobart had been settled, but only members of Unite or the United Road Transport Union would receive compensation.
“All drivers working for Eddie Stobart will benefit from the higher rates of holiday pay for the 28 days leave a year,” he said.
Stobart declined to comment.