UK workers are simply too busy to take their holidays, with almost £4bn worth of work going unpaid each year.
A poll shows that employees fail to take three months of holiday entitlement over the course of their working lives, with men the worst offenders.
Around one in three men and one in six women feel they have too much on their plate at work to take their full holiday entitlement.
The research, by employee benefits firm youatwork, suggests that up to 50 per cent of staff would like to trade in some of their holidays for other company benefits.
Only around 12 per cent of the 1,000 workers questioned said they were currently able to swap holiday entitlement for other benefits.