Around 16% of firms will see their levy bills rise in 2017.

But contractors are warning that changes to the current system will actually start this April despite the CITB publicising the 2017 date.

One contractor told the Enquirer:  “Revised levy bills will have to be paid in 2017 – but it is from this April that the bills start accruing.

“For example, if I hire an electrician, plumber and flooring contractor in March 2015, there will be no CITB levy because supply and fit subcontractors are exempt under the old levy.

“But from 6th April 2015, if I hire an electrician, plumber and flooring contractor I will have to pay the new CITB Levy on their works because supply and fit subcontractors are not exempt under the new rules.

“The total of the new levy liability for the year ended 5th April 2016 will have to be paid in 2017.

“A lot of contractors will not realise that they have to pay the new levy on these works because it has been publicised that it will be ‘implemented in 2017’.

“In 2017 it is too late to do anything about it as the liability was incurred from 6th April 2015 to 5th April 2016.

“If HM Revenue & Customs put up income tax by 1.25% for the year 6th April 2015 to 5th April 2016, then a self employed person would not have to pay the tax bill until January 2017.

“But HMRC would not get away with saying it will be ‘implemented in 2017 -it is being implemented from now.”

Another construction boss added: “The CITB is obviously sensitive about this issue and has been pretty sneaky in the way it has worded all this.”

Gillian Econopouly, Head of Policy at CITB, said: “Levy simplification came about following an extensive consultation, through which industry told us that they wanted a fairer, more straightforward system.

“The changes, coming into force in 2017, will  leave most firms unaffected, although Levy charges will rise for a minority. Any alterations will be based upon staffing levels at companies from April 2015.

“Details of the new system have been communicated to all 75,000 registered construction employers by two direct mailings, in July and November 2014. Therefore, we hope that these changes do not come as a surprise.

“We believe Levy simplification, together with reforms to the way we fund training, will provide industry with a modern, skilled workforce to help construction go from strength to strength over the coming years.

“If anyone has concerns about how they will be affected by Levy changes, please click here or contact our Customer Services team on 0344 994 4455.”