The Inland Revenue is to launch a crackdown on professionals and consultants who provide services through intermediary companies.

A spokeswoman said new rules would stop people hiding behind fake personal services firms to avoid tax and National Insurance.

The clampdown could affect a number of consultants and specialists in the construction industry who provide services to specific clients on a regular basis.

The spokeswoman said: “We will be looking closely at the contracts involved in these arrangements. But we won’t check working practices.”

The rules will focus on the rights of a client to supervise or control the activities of workers engaged under service contracts. If a client is deemed to have direct control of operatives within the service company the Revenue will designate them employees.

The spokeswoman said the Revenue was not singling out the construction industry: “We will be looking at all sectors – construction isn’t being specifically looked at.”

Bob Blackman, construction head of the Transport and General Workers’ Union, was sceptical of the effectiveness of the clampdown.

He said: “Most construction contracts bear no resemblance to the way people work. The only way to check for bogus self-employment is to go to sites and see first hand how these people work. The problem is that the Revenue thinks it can find all the answers by looking at contracts that smart accountants ensure are copper-bottomed.”