Head teachers are to vote on whether to take strike action against reductions to their pensions.
The National Association of Head Teachers has announced the date for the ballot as 29 September - with the result due on 9 November.
The union represents heads and senior staff, particularly in primary schools, in England, Wales and Northern Ireland.
There are plans for other public sector staff to protest against pension cuts on 30 November.
The NAHT's leadership had already announced its intention to hold a ballot - and setting the date now means that schools could face disruption during the autumn term.
This could mean that it becomes part of wider co-ordinated action against controversial changes to public sector pensions.
The NASUWT teachers' union is also preparing for a ballot for industrial action - which is also expected to be this term.
During the summer term, a one-day strike over pensions by the National Union of Teachers, the Association of Teachers and Lecturers and the University and College Union saw an estimated 12,000 schools and colleges being closed or facing disruption.
The announcement of the head teachers' ballot date is against a background of continuing talks between unions and the government to settle the pensions dispute.
A Cabinet Office spokesman said: "We are totally committed to genuine engagement with the unions. We have a lot to talk about and there are proposals on the table for discussion."