Campaign against long working hours
Workers have been urged to leave their office on time as part of a drive to highlight the damage caused by the UK's long hours culture.
Ideas include a senior member of staff having a "ceremonial switch-off" at going-home time and wishing everyone a pleasant evening.
A survey of 1,500 people for the charity showed that six out of 10 regularly worked late, with around half blaming their company's culture.
One in 10 said they never found the time to sit down with their families during the week.
Sarah Jackson, chief executive of Working Families, said: "We organise Go Home on Time Day to highlight the impact that long hours at work can have on family life, but more importantly to encourage people to make a conscious decision to have at least one day when they will leave work on time during the working week - not just once, but all year round."
A spokesman for Bisto, which is sponsoring the day, said: "It's encouraging to see that families are still sitting down for dinner together, but it's important that everyone gets the opportunity to share this quality time with each other, especially as our working lives become more stressful and working hours get longer."
Firms were urged to encourage staff to avoid planning meetings or activities that will start within an hour of their usual finishing time, and to consider banning all business travel for the day.