Umbrella companies have become more prevalent in the UK since the British government introduced so-called "IR35" legislation that creates tests[1] to determine employment status and ability to make use of small company tax reliefs. According to criteria set out by the UK Department for Business, Innovation & Skills, there are an estimated 4 million temporary workers in the UK, of whom 1.56 million are "classed as being in a management or senior official role, a professional occupation or an associate professional and technical occupation." It is estimated that 14% of the UK's professional contractors are currently managing their business by working through an umbrella company.[2]