Six teaching unions are urging the government to make its mind up on whether it will back a call for a real pay rise for teachers in England.
Education Secretary Damian Hinds was told schools faced unnecessary uncertainty over what to pay staff next September due to his delayed response.
In May, the official teacher pay review body reported to Mr Hinds but he is yet to publish that report or his response.
But the pay cap of 1% has been lifted for other public sector workers.
In a letter to the Secretary of State, the six unions, including the National Education Union, National Association of Head Teachers and the Association of School and College Leaders, said head teachers and staff were left wondering what is happening.
It said: "The end of term is imminent. Schools in some areas have already closed for the summer."
It added: "Governing bodies cannot discuss how they will implement the pay increase.
"No one knows whether your government plans to support the pay increase with additional funding."
And this meant that schools had not been able to consult with staff and "decide a position before the end of term".
This had led to uncertainty about how to budget.
"The new school year will start in a climate of uncertainty about pay and funding which could have been avoided," the letter added.
The pay review body, the STRB, was asked by Mr Hinds' predecessor, Justine Greening, to reflect the increased flexibility adopted by the government in public sector pay awards after years of restricting pay rises to 1%.
It was also asked to consider evidence of the "national state of teacher and school leader supply", as well as the need for protecting the public purse.
Last year it expressed concerns over the 1% pay cap, which has been in place for eight years.
Schools have repeatedly reported their difficulties in recruiting and holding on to teachers, particularly those in specialist subjects.
The unions have asked for a 5% pay rise which is fully funded - i.e. not to be taken from existing budgets.
The Department for Education said it was considering the STRB report and would respond in due course.
A spokesperson added that it was committed to making sure teaching remains an attractive and fulfilling profession.