Office workers can expect to spend around £40,000 over their lifetime on workplace costs such as teas and coffees, socialising and chipping in to whip-rounds for colleagues, research suggests.
From work clothing to stationery, parties and nights out with colleagues, as well as coughing up cash for leaving gifts and charity requests, the average cost was found to add up to just over £1,000 a year - or around £40,000 over the course of a 40-year working life.
The £40,000 total, calculated by Nationwide Current Accounts, equates to around two years' salary after tax for the average UK worker.
The calculation does not include the cost of daily lunches or travel to work, so the full cost if these were also taken into account would be even higher.
Nationwide commissioned a survey of 2,000 office workers across the UK to make the findings.
The survey found that while men generally tend to be unhappier than women about spending money at work, women are more likely to feel pressured into shelling out for work-related items.
For example, two-fifths (42%) of men were unhappy about spending money at work Christmas parties, compared with just over a third (34%) of women.
But 20% of women said they felt under pressure to spend money at Christmas parties, compared with just 12% of men.
Overall, more than a quarter of people surveyed said they felt pressured when it came to contributing cash towards birthday and leaving gifts, with 28% feeling this way about birthday presents and 27% of people saying this about gifts for colleagues who were leaving.
Nearly a third (32%) said they felt pressured into contributing money to help their colleagues' charity fundraising efforts.
One in 10 (10%) people surveyed spent time with their colleagues outside of working hours on a weekly basis. But more than a third (35%) of office workers surveyed say they do not like to socialise with their colleagues after work.
Alan Oliver, Nationwide's head of external affairs, said: "Working in an office can be an expensive business, especially in big teams. While most people value the camaraderie of working in a team, birthdays, retirements and charity fundraisers can take their toll on our wallets and purses."
Here is how the annual average cost of working in an office adds up, according to the survey for Nationwide Current Accounts:
:: Clothes and bags, £119.16
:: Drinks and nights out with colleagues, £102.24
:: Christmas parties and dinners, £96.48
:: Birthday cards and presents for colleagues, £66.60
:: Coffees and teas, £66.36
:: Sweets and treats, £64.32
:: Technology (such as a tablet, phone, calculator), £58.32
:: Leaving presents and cards for colleagues, £50.28
:: Comfort items (such as tissues, tablets, anti-bacterial wipes and sprays) £49.68
:: Colleagues' weddings, £47.04
:: Charity/sponsorship requests, £44.64
:: Births of colleagues' children, £43.92
:: Secret Santa, £41.88
:: Stationery, £41.04
:: Other equipment (such as pens and highlighters), £38.04
:: Retirements, £39.24
:: Bereavements, £33.96
:: Total, £1,003.20