Overall, FairFX found 26% of employees fiddle expenses, but the worst offenders came from the promotions industry, where 67% of staff confessed to wrong-doing, followed by graduates and trainees (43%).
The most popular spend passed off as expenses is food and drink (39%), followed by travel (24%) and accommodation costs (19%).
Staff from the financial sector fiddle the most - claiming an average of £1,070 per year.
Stephen Heath, chief executive of FairFX said: "Businesses need to find a new approach to managing employee expenses. A prepaid corporate card, for example, could erase fraudulent claims, cut employee administration time and ensure the expenses process is easy and cost efficient."
