Almost one in three social care staff work at least 10 hours over their contract each week, according to a Community Care poll.
The online survey on CommunityCare.co.uk revealed that more than one in ten respondents work more than 15 hours over their contract each week, the equivalent to three hours a day.
More than a third work between 5 and 9 hours more than they are supposed to. Just 5% of respondents said they worked their contracted hours each week.
The findings are published on National Work your Proper Hours Day and the TUC is urging managers across Britain to take their staff to lunch to say thank you for all the extra work they do.
The total value of unpaid overtime across Britain is almost £25 billion in 2007 with almost five million employees working overtime for no extra money, according to the TUC.
Women who do not have children are amore likely to do unpaid overtime than childless men, but once women have children, the percentage if them working overtime for no money drops from 24.2 per cent to 17 per cent.
TUC general secretary Brendan Barber said: “Long hours working and unpaid overtime is not confined to any particular group in the workforce, and after falling slightly is back on the increase. We are not saying that we should turn into a nation of clock-watchers, or that staff should not put in extra effort when there is a rush or a crisis.
“But those extra hours are too often taken for granted and, if allowed to build up, can damage people’s health, relationships and morale at work. Fairer workloads, better management and a change in culture could make a real difference,” he concluded.