Police Scotland has spent almost £2 million buying back time off in lieu (TOIL) from police officers for 2018/19.
Five years ago this action was costing them just £72,000.
The escalating costs were revealed by a Freedom of Information request.
Calum Steele, general secretary of the Scottish Police Federation, said that officers can be pressured not to work overtime for payment in the belief that saves money, only for them then to face obstacles in getting the time off meaning it has to be paid eventually.
Figures show the cost of TOIL rose from £71,915 in 2013/14 to £1,856,677 in 2018/19.
Mr Steele said: “There is a bit of an illusion that overtime is worked and doesn’t have a cash cost.
The ultimate end of buying TOIL demonstrates that officers are not getting time back.
“We also know that for financial reasons, pressure is put on officers not to take TOIL.
“This, in turn, causes pressures, stress and fatigue for officers.”
Scottish Conservative shadow justice secretary Liam Kerr said the issue flagged up a police staffing crisis.
“This arrangement may well suit some officers grateful for the extra cash,” he said.
“But it also points to a police force which doesn’t have the manpower to cover rotas.
“The SNP has cut police budgets to the bone and there could well be consequences for public safety if that continues.
“Police officers need and deserve a holiday more than most, given the nature of the job. It’s important they don’t come under pressure to forfeit that.”
David Page, deputy chief officer, said: “Police Scotland inherited TOIL liability worth approximately £6.4 million from legacy forces and overtime from the Glasgow 2014 Commonwealth Games.
“Policies on TOIL from individual legacy forces were inconsistent and a national policy had to be established. This debt has now been reduced to around £750,000.
“Since 1 April 2015 we have ensured TOIL after this date has been converted to payment on a 90-day basis in line with regulations.
“A further change was announced in December 2017 that TOIL before 1 April 2015 would also be converted to payment to allow us to manage our costs.
“Due to these changes and a number of high-profile events, TOIL buy back has gone up in recent years.
“However, these costs are now better managed and accounted for as part of divisional overtime budgets.”