This month a government-backed report recommended a new mandatory requirement for those aiming to become headteachers.
This would replace the Standard for Headship qualification, which is voluntary and can be attained either before candidates apply or after they have started in the role.
Headteachers’ unions said the new qualifications, which would be effective from 2017, risked narrowing the field of prospective heads without necessarily ensuring more talented and suitable candidates would come through.
Ken Cunningham, general secretary of School Leaders Scotland, said any leadership development should not be a barrier to progression, but should be about enhancing the capabilities of future leaders.
“We don’t want an absolutely definitive statement about what you should achieve before applying to become a headteacher.
“If you make achieving the qualification too rigid then that runs the risk of putting people off, and we are struggling as it is to get good people in post.”
The report, Teaching Scotland’s Future, stated: “Within five years all aspiring heads should have an appropriate qualification or professional award in leadership, as evidence of meeting the Standard for Headship.”
Greg Dempster, general secretary of the Association of Headteachers and Deputes in Scotland, said the union would support the introduction of a qualification for all that improved headship.
“However, the mechanism very much needs to be in place so that it does not become a barrier to getting people into headship. The time deadline is five years so they would need to have a qualification established and enough candidates coming through it to allow there to be competition still for headteacher roles. You would have to have considerably more people coming through the qualification than there were actual vacancies.”
Dr Alasdair Allan, the minister for learning, said the unions would have a key role in formulating any new qualifications.
“There is no clear delineation of how it will be developed and it is not a question of trying to undermine the position of existing heads or putting off those who want to become a headteacher.
“The success of schools depends on good leadership and we want to make sure people coming into the role do so with confidence.”
Large numbers of heads are due to retire within the next few years and incumbents say increasingly hard working conditions are deterring potential candidates.
Cuts to the number of deputes and principal teachers – who often become headteachers – will also make it harder to recruit successors, unions say.