Special needs teaching assistant Linda Hands was looking forward to a little extra in her pay packet under the workforce agreement.
But she was furious when she heard that employers were telling schools they need pay new higher- level teaching assistants higher rates only for the time spent carrying out specific duties.
"I am shocked at the employers' attitude over this. The remodelling process really should have enhanced our status, but this is just another blow to school support staff," she said.
Ms Hands works at Hebden Green school in Winsford, Cheshire, and had initially thought that becoming an HLTA under the school workforce agreement would be a "fantastic" career move.
But advice from Essex council sent to schools, and since backed by the teachers' employers' organisation, has changed her mind.
The authority says it anticipates schools paying staff "the higher level for the period they work at the higher level and not necessarily for the whole of their time, not least because of the cost implications of an alternative arrangement".
Mike Walker, of the employers' organisation, said he expected most schools to go down that route. "There is no point in paying for skills that are on the shelf," he said.
HLTA status was brought in as part of the school workforce agreement to give support staff the training to enable them to take on tasks such as preparing, delivering and marking lessons.
Bruni de la Motte, Unison education officer, said the union would first raise the matter with other signatories to the agreement but it was firmly opposed to the plan and strike action was an option. "Contracts where you have little bits and pieces are what we had in the past and we were hoping we had overcome that," she said.
The row comes as both local authority officials and training providers say that demand for places on HLTA training courses has been lower than expected.
Roz Osbourne, senior administrator at Weymouth college, said it had had to cancel the shorter three-day assessment courses for HLTAs because of a lack of demand.
Potential HLTAs had felt they would not get any financial or career reward for the qualification and in some cases heads were refusing them permission to go on the course, she said.
John Parker, Essex council's teacher recruitment officer, said that so far his authority had only allocated around half the money it had received for HLTA training.
It had hoped to fill all spaces by the end of the summer term but it had had to advertise three times. He thought other authorities had had similar experiences.
Dave Powell, organiser for the GMB support staff union, said the lack of national HLTA pay rates and job descriptions was discouraging applicants.
But the Teacher Training Agency said 5,500 of the 7,000 places for the 20045 financial year were taken and local authority feedback suggested there was more than sufficient demand to fill the rest before the end of the year.
* Two further school support staff strike dates have been set in Brighton and Hove for next Friday and January 6. Unions claim the council is cutting the number of weeks staff are paid for, in order to fund a pay rise.