The think tank’s findings show that 60% of the growth in self employment since 2009 has been in ‘privileged’ sectors, despite them making up just 40% per cent of the self employed. The fastest growing sectors have been advertising (100% growth), public administration (90%), and banking (60%).

The remaining 40% of the growth in self employment has come in more ‘precarious’ sectors, such as construction and cleaning. The Foundation notes that despite the focus on Uber in recent years, the sector that includes taxis is actually only up 7% since 2009, a third of the 22% growth in self employment up as a whole.

However, these slow growing precarious sectors still make up the majority (60%) of the self employed workforce, which is why their typical weekly earnings remain well below that of employees at around £240 a week.

The Foundation says that the sharp rise in high-paying ‘privileged’ sectors is due in large part to the big tax advantages now associated with self employment. It notes a high-earning self employed worker costing a firm £100,000 enjoys more than a £7,000 tax advantage over a similarly expensive employee.

In contrast, a self employed worker in a precarious sector costing a firm £10,000 enjoys a minimal tax advantage of just £200 but still misses out on important rights, from the National Living Wage to statutory maternity and sick pay and protection against unfair dismissal.

The analysis finds that a key reason behind the tax advantages enjoyed by the self-employed is their exemption from employer National Insurance contributions. It shows that lower National Insurance contributions by and for the self employed are set to cost the Treasury more than £6bn a year by 2020, a 20% increase on its current cost. Nearly 60% of that tax benefit goes to the ‘privileged’ sectors.

The Foundation says that alongside looking at the rights of the self-employed, which is currently the focus of the review of modern employment being carried out by Matthew Taylor for the Department for Business, Energy and Industrial Strategy, it is time to look again at the tax regime for self-employment. It argues that government should reduce the incentive for people to be self-employed given the risks to the public finances, to productivity and to those that may not want such precarious work.

Adam Corlett, economic analyst at the Resolution Foundation, said: ‘Rising self-employment has been the biggest jobs story of the last decade, accounting for almost half of all employment growth since the financial crisis.

‘With the number of self-employed workers approaching five million, we need to start addressing some of the challenges it brings. This should include more security for workers at the bottom end of the market, but reforms should also reduce the unfair tax advantages that the wealthy self-employed particularly benefit from.’

A tough gig? The nature of self employment in 21st Century Britain and policy implications is here.