Philip Hammond is set to deliver the UK’s Spring budget today at 12:30 pm where it is expected that a number of changes will announced.

Among the expected budget changes include the closing of loopholes that allow many self-employed workers to pay less tax, however it is also expected that their worker rights should improve. The Guardian reports that the Treasury is concerned that the growing prevalence of self-employment is not just driven by entrepreneurialism in the “gig economy”, but by tax avoidance, which will progressively undermine the UK’s tax base.

Currently, the self-employed pay 9% national insurance contributions (NICs) on their earnings above £8,060, compared with 12% for employees.

Simon McVicker, director of policy at IPSE, the trade body for self-employed workers, said, “If the increase goes ahead, the government should commit to righting some of the unfairness in the tax system for the self-employed. Any big changes to tax policy should be preceded by a proper consultation.”

Julia Kermode, chief executive of the Freelancer & Contractor Services Association, told the Chartered Institute of Personnel and Development that she did not accept there was a tax gap, particularly as self-employment has remained at 15% of the workforce while permanent employment continued to rise.

“Lots of people bang on about the rise of self-employment and how this is a real concern, but this rise is actually in line with the rest of [the] workforce. The problem is not with the individual choosing to become self-employed and then not paying tax, the problem is with unscrupulous employers self-employing their staff and exploiting them. Individuals are paying tax at the correct rate; no one goes into self-employment to pay less tax.”

Hammond is also expected to make announcements regarding tax rises, wages, social care, skills training as well as addressing the UK’s preparation to exit the EU.