TWO-THIRDS of supply teachers have been asked to sign contracts with umbrella companies that allow agencies to “exploit” staff and avoid tax, new figures revealed yesterday.

A poll of over 1,000 supply teachers by NASUWT found that 66 per cent were asked to surrender pay and employment rights by signing up to umbrella companies — some based offshore. 

The scale of the swindle, which is robbing workers and taxpayers, was uncovered as the union calls for government action to stop the exploitation of supply teachers at its Cardiff conference today.

Labour’s shadow schools minister Kevin Brennan told the Morning Star he was “very concerned” at the survey’s findings. 

Supply teachers are told signing up to umbrella companies will allow them to increase their take-home pay by claiming expenses under their contract worker status. 

But NASUWT argues the arrangement allows agencies, which take up to a third of their clients’ wages in commission, to exploit supply teachers. 

Its survey found that teachers were regularly denied pay, pensions and decent working conditions. 

In an anonymous response to the survey, one teacher wrote: “I have loved doing supply in the past. “But, unfortunately, now many schools are using agencies in which a third of the pay is taken off and one cannot pay into the teachers’ pension.

It is demoralising and I can’t see a future.”

Some teachers are also forced to pay both the employers’ and employees’ national insurance contributions — 25 per cent of their wages — because the umbrella company which employs them is based offshore. 

The employers’ contribution is never paid in many cases, leaving millions of pounds missing from the Treasury.

Taxpayers are then forced to make up the shortfall — despite around 200 teaching agencies earning £293 million from state-funded schools alone in 2009-10. 

Tory Chancellor George Osborne announced plans to “review the growing use” of umbrella companies in his Budget last month. 

But NASUWT general secretary Chris Keates said his “belated” announcement has not stopped the exploitation of supply teachers. “A review will not resolve the exploitation and lacks the urgency which should be demonstrated when tax is being avoided and workers exploited,” she said. 

And National Union of Teachers general secretary Christine Blower said the union was “very concerned about the umbrella companies. 

“But they are only part of the problem. We need urgent action to make supply agencies give teachers fair pay, access to pensions and stop public money for schools being siphoned off into agencies’ pockets.”International Subcontracting Solutions, which is based in the Channel Islands, is one of the few umbrella companies to be named and shamed. 

A BBC investigation in 2012 found it had avoided millions in national insurance contributions for 24,000 teachers on its books at the time. 

Labour has committed to stop umbrella companies “exploiting tax reliefs” in its first finance Bill if it’s elected on May 7. 

Mr Brennan told the Star: “I don’t think anybody believes that Osborne is sincere about wanting to enhance workers’ rights and he certainly shouldn’t be taken at his word.

Ed Miliband has made it clear: We want to crack down on some of the activities of umbrella companies as well as exploitative zero-hours contracts.”