The six unions have jointly taken legal advice on how to proceed and are also consulting the Equal Opportunities Commission. The unions say the changes are discriminatory, as the vast majority of teachers who will be affected are women. Almost half the new recruits to the profession are women returners.
This year's report of the School Teachers' Review Body on pay said: "We recommend that experience points for teachers who have left teaching on retirement terms should not be regarded as a permanent entitlement for the teachers concerned if they wish to surrender them voluntarily when returning to teaching or . . . moving schools."
The review body, chaired by John Gardiner, had been under pressure from Education and Employment Secretary Gillian Shephard to, in the words of the report, "enable experienced teachers to compete more effectively for jobs by allowing them to surrender experience points". The report also recorded that heads generally regarded part-time returners with expertise and experience as good value, although they were relatively expensive.
The unions believe the change will force experienced teachers to make themselves cheaper in order to be able to compete for a new post. They will now either seek judicial review or sponsor a case in the High Court in order to get a ruling.
Mr Gardiner was warned, before the report was published, by union officials and the national employers' organisation the change could contravene equal opportunities policies and equal pay legislation.
The official consultation period for the review body's recommendations and Government's acceptance of the report end on March 16.
In a letter to the EOC the teacher unions say governors under budgetary constraint will put pressure on returners to "voluntarily" surrender their experience points. Women who hold fixed-term contracts or undertake supply work could also be adversely affected.
Mary Howard, the National Association of Schoolmasters Union of Women Teachers' principal officer for education and equal opportunities, said: "It is discriminatory and could disadvantage a significant proportion of our profession. The majority of women have to take time off for care and commitments at some point. We are already concerned that women are not as fully represented in the better-paid end of the profession."