Primary heads have called for a revision of the job-sizing toolkit as part of a "wholesale review" of the 2001 teachers' agreement.
The Association of Headteachers and Deputes in Scotland (AHDS) said it did not want to see local authorities "cherry-picking" bits of the agreement, such as the removal of reduced class-contact time.
But the AHDS wants the Scottish Negotiating Committee for Teachers to revisit the job-sizing toolkit in a bid to set clearer differentials between promoted posts in schools.
The current model was a "hurdle" to headteacher recruitment and had resulted in some principal teachers earning more than deputes and some deputes earning more than heads, said general secretary Greg Dempster.
"The job-sizing toolkit was a well-intentioned system for rewarding work but the reality is different," he said, in his address to the association's annual conference in Cumbernauld last week.
"It has created a large hurdle in attempts to recruit new headteachers. This has to be addressed in any review. As an association we will fight for that."
The AHDS is arguing that deputes' salaries should never be higher than those of headteachers, unless they are working in "exceptionally large primary schools".
"A new system for arriving at school leaders' salaries should better protect career pathways, making sure there are adequate differentials between different levels - principal teacher and depute, and depute and headteacher.
"There is then a financial incentive to move up the career ladder. If we do not get job-sizing and promoted salaries correct, it will not matter what else we do to make headteachers' jobs more appealing and desirable," said Mr Dempster.
Rather than the myriad factors currently taken into consideration, a new job-sizing toolkit should concentrate on just three: the postholder's position in the school, ie, head, depute or principal teacher, which would determine salary scale; the school roll (as a headcount, including nurseries or SEN bases); and the number of staff for whom they are responsible, ie, a headcount of the number of staff the postholder reviews personally plus those their subordinates review.
"The tool currently includes your role, the school's roll, free school meal entitlement, areas of responsibility - the list goes on," said Mr Dempster. "It is too complicated and people don't understand how salaries are arrived at."
Glasgow City Council leader Gordon Matheson has made it clear he wants sections of the 2001 teachers' agreement to be reopened. He estimates that if teachers spent an additional 30 minutes a day in contact with their classes, the council would save pound;15 million annually, while leaving teachers with 10 hours' paid preparation time every week.
Other councils are known to be angling for changes to teachers' conditions and pay and two weeks ago, Education Secretary Michael Russell told the Scottish Parliament's education committee: "Any agreement that's 10 years old will probably need revisiting."
Mr Russell stressed that any changes could only be made through discussion involving the Scottish Government, local authorities and education trade unions in the tripartite Scottish Negotiating Committee for Teachers.
It is questionable how much influence AHDS could hope to have. The union withdrew from the teachers' side of the SNCT because it was dominated by Scotland's largest teaching union, the Educational Institute of Scotland.
For a period it acted as a formal adviser to the management side but that relationship ended recently, when budget cuts began to bite and Cosla became concerned that councils would not feel able to speak freely in front of it. Now, if AHDS wants to influence decisions being made by the SNCT, it feeds its argument to the local authorities' umbrella organisation, Cosla.