Nearly half of teachers say their schools have failed to implement a deal to reduce their workload in full, five years after it first came into effect, a TES poll has found.

Responses from 3,453 teachers, suggest that even where the school workforce agreement - signed by Government, unions and employers in 2003 - has been introduced, it often fails in its central aim.

The deal had made “no difference” to the workload of 48 per cent of teachers, and another 10 per cent said it had actually increased it. It is supposed to mean teachers no longer have to carry out more than 20 administrative tasks, such as filing; that any cover they provide is limited to 38 hours a year; and to guarantee that 10 per cent of their timetabled teaching time is set aside for planning and preparation.

In most schools, support staff have filled the gaps. The need for teachers to supervise them may explain why some say the deal has increased their workload.

Only 3.4 per cent of those surveyed said it has led to anything more than a small reduction. One teacher wrote: “I need to check up on admin work, which is often done by low-pay, low-skills staff.”

The NASUWT began a major campaign this summer calling on teachers to report their school if it was breaking the law by not abiding by the deal. Chris Keates, the union’s general secretary, said: “Five years on after the agreement there is no excuse for every single part of this not being in place.”

The TES survey, commissioned for a special investigation to be published next week to mark the 5th anniversary of the workload deal, found that 47 per cent of teachers said their school had not implemented the agreement in full. Only a quarter said their schools had done so, with another 28 per cent saying they did not know.

Hilary Emery, from the Training and Development Agency for Schools, which is responsible for supporting schools in implementing the deal, said teachers should contact their union representatives or local authorities if they felt the agreement was not in place. There was no room for complacency.

“Our evidence is that all schools almost without exception have implemented the key elements as they were rolled out,” she said.

Last week School Teachers’ Review Body research showed the first across the board increase in teachers’ working hours since 2000.

A spokesman for the Department for Children, Schools and Families said: “It is unacceptable if heads’ or teachers’ contractual rights are being ignored and the national agreement is not being implemented. Ultimately, it is down to employers themselves to support their staff properly. We are working closely with all the social partners to make sure this happens.”