It accuses the employers of trying to rewrite the committee's agreement on pay and grading by delaying it for up to 18 months.
Stalemate in the previous year led to the first national strike by members of the Community and Youth Workers' Union (CYWU). The expectation that new pay scales would be backdated to last September was a key factor in ending the industrial action.
The staff side says that not backdating could cost some people more than pound;1,000. "Documents agreed by both sides in May show the agreement provided for existing scales to be replaced by new ones from September 2003," said Andrew Morris, JNC staff side secretary.
"During June, however, it became clear that the national employers were seeking to rewrite the agreement. They want individual employers to be able to delay moving workers on to new scales up until April 2005."
Employers say their position has been clear all along - and that it was accepted by the staff side. "We offered a rise of 2.7 per cent from September 2003 and 3.3 per cent from six months after that," said principal negotiating officer Allison Wheeler. "We believe the misinterpretation is on the staff side. We're trying to play it straight."
The staff side is now seeking mediation through the arbitration service ACAS.