TENS of thousands of Scottish workers could be in line for large payouts following a landmark court ruling.
The judgment, which will cost employers millions of pounds, has been described as the most significant development in employment law since women secured equal pay.
It means employees across the UK will now be able to claim holiday pay for regular overtime and shift allowances.
The payments could be back-dated for 16 years, prompting fears that the costs could put some firms out of business.
It was initially thought a European Court of Justice judgment from May only impacted on workers who earned commission, but lawyers now claim it has much wider implications.
David Martyn, an employment lawyer with Thompsons solicitors, said: "It was thought that it would only apply to people in sales jobs who made extra cash from their sales commission. But it also applies to the tens of thousands of Scots who rely on extra payments from overtime and nightshift work just to make ends meet.
"For these workers, these so-called 'extra' payments are just a normal part of their pay packet.
"We believe that workers across all sectors will qualify for back-dated holiday pay. You might be a car salesman who relies on commission, or you may work unsociable shifts in the public sector and receive extra payments for that. We also believe that call centre workers who receive regular bonus money will qualify."
The ruling is the result of a case brought by a British Gas employee who received only his basic pay, without commission, when he went on holiday.
This meant he was losing more than half of his average earnings during annual leave and the court ruled this was unlawful under the Working Time Directive.
Suzanne Craig, legal officer for the union Unison, which raised the British Gas case, said: "The court has said that holiday pay should be your normal pay and that can be taken to include regular overtime and shift payments - the court is clear on that."