The Chancellor announced in the Budget that the main rate of Class 4 NICs for self-employed people will increase from 9% to 10% from April 2018, with a further increase to 11% in April 2019. Currently, employees pay 12%, while the move follows the previous decision to abolish the Class 2 flat rate £2.80 a week on earnings above £5,965 from April 2018.

The difference in NICs in the past has been in order to reflect that the self-employed do not have access to benefits such as paid holiday, paid sick leave, a state pension and other benefits, but Hammond said in his speech such ‘dramatically different treatment of two people earning essentially the same undermines the fairness of the tax system’.

The announcement provoked strong opposition from MPs including Conservative backbenchers after it appeared to break a manifesto pledge the party had made to freeze NICs in its campaign for the 2015 General Election.

But despite offering a defiant defence of the decision, describing it as ‘simpler, fairer and more progressive’ in a speech at a European summit in Brussels, the prime minister said the rise will be ‘brought forward’ in the autumn and will not be included in the Finance Bill.

The additional time will allow the government to make the case for the rise and will come in following the publication of the Matthew Taylor report on the changing nature of working practices, including the gig economy and self-employment.

It is expected Taylor will recommend enhancing employment rights and benefits for the self-employed.