According to the TUC if employees who regularly put in unpaid overtime worked all their hours from the start of the year, the first day they would get paid would be today (Friday 24 February). The TUC has named this Work Your Hour Proper Hours Day (WYPHD).
The TUC analysis of Government figures shows over the last decade the number of workers doing unpaid overtime has increased by 96,000. Given the growing size of the working population, this means that the likelihood of doing unpaid overtime has fallen by 0.2%.
But the analysis reveals sharp age disparities. The proportion of workers in their early 20s doing unpaid overtime has fallen by 36% in the last decade, while the likelihood of workers in their early 60s doing unpaid overtime has increased by 45%.
A quarter of a million more workers in their late 50s and early 60s did unpaid overtime in 2011 than in 2001. Fears about a loss of income after retirement mean that more people are working past their traditional retirement age. This is leading more older workers to do unpaid overtime, says the TUC.
The likelihood of doing unpaid overtime increases the longer someone has been in their job. Workers who have been in the same post for at least ten years are twice as likely to work unpaid overtime (25%) as those who have been working for less than a year (12.5%).
Workers in their late 30s are still the most likely to work unpaid overtime, with over one in four employees in this age bracket (26.6%) regularly putting in extra hours for free.
The TUC analysis also shows that teachers are the most likely to do unpaid overtime, with media professionals and managers in financial services, health and social services also featuring highly in the charts.
At least half of all workers in these professions regularly put in unpaid hours, showing that a long hours culture is now 'part of the norm', despite much of it being unpaid, bad for their health and not productive, says the TUC.
Across the UK around one in five workers (5.3 million people) put in an average of 7.2 hours of unpaid overtime per week last year, worth around £5,300 a year per person - and a record £29.2 billion to the economy.
TUC General Secretary Brendan Barber said: "Over the last decade, more people are working well into their 60s - and many of them are putting in extra unpaid hours too.
"A lot of older workers are keen to reduce their hours as they approach retirement, but many of them have to top up their contracted hours with extra working time for free.
"One in five workers regularly do unpaid overtime but it's becoming the norm in far too many workplaces. Whilst most people have no objection to putting in some extra hours to help their employer through a busy period, an entrenched long hours culture causes stress, health problems and lower morale.
"We're asking employers to support Work Your Proper Hours Day today by encouraging staff to take a proper lunch break and leave work on time. Given that managers themselves tend to do a lot of unpaid hours, taking a few simple steps to address long hours problems will benefit everyone in the workplace."