Union leaders are calling for a new right to switch off outside working hours after new research suggested employers enjoyed £27 billion of free labour last year because of unpaid overtime.

The TUC said its study indicated that 3.8 million people did unpaid overtime in 2021, putting in an average of 7.6 unpaid hours a week, equivalent to £7,100 a year.

The figures show that Government promises to “build back better” are not being fulfilled when it comes to workers being paid for all the hours they work, said the union organisation.

The TUC published the figures on its annual Work Your Proper Hours Day, when workers are encouraged to finish on time with the support of their employers.

We’re calling on people to take your full lunch break and go home on time, and we’re calling on managers to encourage their staff to finish on time and to lead by example

Unpaid overtime was higher than in 2020 following a collapse in working hours during the first year of the pandemic, said the report.

Between 2020 and 2021 the number of workers doing unpaid overtime increased by 427,000, the TUC found.

As in previous years, teachers were high on the list of those doing unpaid work, as well as managers and directors.

People who work from home are more likely to do unpaid overtime, while those who never work from home are more likely to do paid overtime, it was found.

The TUC called on the Government to bring forward the “long-promised” Employment Bill and strengthen protections against overworking and burnout, including a day-one right to flexible working.

TUC general secretary Frances O’Grady said: “Most of us are happy to put in some extra time when it’s needed, but we should get that time back when it’s quieter. Nobody should end up doing work they don’t get paid for.

“So today we’re calling on people to take your full lunch break and go home on time, and we’re calling on managers to encourage their staff to finish on time and to lead by example.

“Britain is now facing both labour shortages and a cost-of-living crisis.

“If the Government does not take action to support workers, they will end up working longer hours for less pay.

“The Chancellor should use his Spring Statement to set out plans to tackle labour shortages in public services, and to fund training where there are skills shortages.

“And he should come forward with a plan to get wages rising across the economy.

With home-working expected to stay higher after the pandemic, it is important that employers respect rights to clock off and switch off at home

“During the pandemic, we’ve seen an increase in unpaid hours worked at home.

“With home-working expected to stay higher after the pandemic, it is important that employers respect rights to clock off and switch off at home.

“Ministers should help by bringing in new rights to flexible working for everyone, including a right to switch off outside working hours.”

Dr Mary Bousted, joint general secretary of the National Education Union, said: “Yet again teachers rank very highly in the list of professions working the most unpaid overtime.

“This is a problem that has been going on for decades.

“The Government launched an effort to tackle workload in 2015, but it became a damp squib, achieving very little.

“Successive education secretaries have been unwilling to accept their role in the extraordinary numbers of hours teachers are expected to work, yet workload is the main reason they are seeing the departure of so many teachers, heads and support staff.

“It is generated by a tick-box culture of excessive accountability, which chews up many hours that could be better spent on child-focused work and causes people to work long into the evening.

“This is not a sustainable situation, and it is leading to burnout.”

Dr Patrick Roach, general secretary of the NASUWT, said: “The pandemic has undoubtedly exacerbated the problem of excessive workload within teaching still further, with nine in 10 teachers in our recent wellbeing survey saying they have experienced more work-related stress in the last year and over half saying that levels of workload are the biggest contributor to the growth in that stress.

“At the same time, teachers are working far in excess of their contracted hours for what, in real terms, amounts to less pay, thanks to the Government’s decision to impose a pay freeze on the profession for 2021/22.”

Paul Whiteman, general secretary of school leaders’ union NAHT, said: “Even before Covid-19, it was widely acknowledged that teachers and school leaders’ working hours had reached unsustainable levels.

“During the pandemic, their working week has got longer still. OECD data shows that teachers in this country work longer hours for less money than their international peers.

“The Government urgently needs to do more to convince both graduates and experienced teachers and leaders that education is an attractive, viable and sustainable life-long career choice.”

Angela Rayner, Labour’s deputy leader and shadow secretary of state for the future of work, said: “Strengthened rights at work, more control over our lives and a better work-life balance will give workers security in their jobs and the respect they deserve.

“Flexible working is not just working from home, it’s about work fitting around our lives rather than dictating how we live.

“In a new digital world our employment rights need to keep up. We know workers need to be able to disconnect at home, that is why it is Labour policy to provide all workers with the right to disconnect outside of working hours.”

A Government spokesperson said: “We are committed to strengthening workers’ rights and ensuring all employees can enjoy a fair work-life balance, which is why we have already consulted on making flexible working the default, unless employers have a good reason not to.

“To go further, we have also set up a Flexible Working Taskforce, to help us properly understand the profound changes in ways of working that are emerging as a result of the pandemic.”