Education Secretary Gillian Shephard has shelved proposals to change the national pay and conditions agreement after a barrage of protest.
Unions said the plan would break equal pay legislation because most teachers returning to work after a break are women, and won backing from the Equal Opportunities Commission.
Mary Howard, principal officer for education and equal opportunities at the National Association of Schoolmasters Union of Women Teachers, said this week: "We are very pleased Mrs Shephard has backed down.
"It would have been bad news for women returning to work or moving jobs because it would have meant them being put under pressure to accept lower salaries than their male colleagues.
"We could not accept women being allowed to work for less even if they wanted to because it would have meant undercutting other people. It would have lowered salaries generally, and would have been patently unfair."
Six teachers' unions joined forces earlier this year to fight the proposal put forward by the pay review body after pressure from Mrs Shephard.
The review body's report said the move would enable experienced teachers to compete more effectively for jobs, and added that heads generally regarded part-time returners with expertise and experience as good value although relatively expensive.
But the unions said it would force experienced staff to make themselves cheaper and warned it would break equal opportunities policies and equal pay legislation.
Mrs Shephard also announced that she had accepted the review body's recommendations for introducing an annual performance review for heads and deputies, and to create half points on the pay scale for classroom teachers.