Using Office of National Statistics (ONS) data, price comparison website Small Business Prices found that women are driving up the national average for overtime (3.9 hours), working 4.5 hours extra each week, compared with the 2.8 hours worked by men.
The company attributes the difference to women having the mentality that they must work twice as hard as men due to societal inequality.
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Anna Whitehouse, founder of parent news blog Mother Pukka, and champion of the platform's flexible working awareness campaign Flex Appeal, said that employers need to take more responsibility to ensure that women are not being punished for taking on more flexibility than men.
Speaking to HR magazine, she said: "Employers need to monitor women who are working flexibly or part-time to ensure that they aren’t being overworked and underpaid, and that they are being rewarded for the role they are doing in the agreed hours. We need to start promoting part-time workers and celebrating flexible working with recognition and acceptance.
“Women are more likely to be working in part-time or flexible roles than men. It can be easy to over-work when you are working ‘less hours’ [on paper] to show that you can do the job, and hit your targets in a workplace that rewards presenteeism and showing up."
The research showed that UK employees are working the equivalent of 22 days in overtime every year, worth over £2,700.
Workers in agriculture worked the most overtime hours, averaging 6.6 extra hours a week.
David Frost, people and organisational development director at agriculture corporation Dole, said that though his organisation does not have employees in the crop production sector in the UK, from experience, higher overtime could be caused by two factors.
Speaking to HR magazine he said: "I would suggest that two likely drivers for higher overtime levels will be a general shortage of people available and/or applying to work in the sector, leading to pressure on resources; and the day-to-day variability of activity levels driven by weather, crop yield and varying customer demand."
Though overtime may be optional in some cases Alex Bearman, partner in the employment team at law firm Russell-Cooke, warned of employers exceeding the legal limit.
He told HR magazine: “In the UK the ability to require staff to work overtime is limited by a rule which provides that working time should not exceed 48 hours per week on average and there are potential criminal sanctions for the employer if this limit is breached.
“In some cases, long working hours can lead to stress-related absences and mental health problems. This is something which employers need to be mindful of pursuant to their duty to take reasonable steps to look after the health, safety and welfare of their employees.”