Primary heads in Highland have opened a campaign on behalf of colleagues around the country who say their role in promoting the threatened national language has been devalued by the PricewaterhouseCoopers (PWC) toolkit for assessing the worth of promoted staff.
One head says he was told by a PWC team leader that Gaelic-medium education was similar to having "a number of pupils from ethnic origins other than GB".
He said: "It was reckoned to be non-PC to take this into account."
Another head describes the questionnaire used to gather information as "seriously flawed" since it took no account of Gaelic-medium education in primaries. "This represents a significant error on the part of the compilers of the questionnaire," he said.
A third head was "quite astonished" that the work demanded of headteachers with Gaelic classes was considered to add nothing to the size of their posts.
"Under the McCrone agreement, the job-sizing mechanism was supposed to take in factors such as curriculum development and quality assurance and whole-school policy implementation. In the case of Gaelic-medium education, the methodology devised by PWC has not done this," he said.
The head added: "Gaelic-medium nearly doubles the national testing load of a school implementing extra national tests. A Gaelic-medium school has to implement an extra set of national 5-14 guidelines, guidelines which do not just apply to one subject but to all subjects as separate curricular materials and policies apply to each component of the 5-14 curriculum."
A Scottish Executive spokesman said: "The SNCT (Scottish Negotiating Committee for Teachers) looked at the issue of Gaelic-medium education as part of the discussions in the job-sizing toolkit but concluded that it did not itself increase the job weight. However, the job-sizing toolkit is flexible and does take account of the number of curriculum areas for which senior managers are responsible."
It is suggested that senior staff should be given extra points if they have more staff to manage because of Gaelic teaching or if they personally take responsibility for it.
If staffing is deemed to be no greater than in a school of similar size or if other staff are responsible for the curriculum, heads would not gain any further points.
No one from Highland's education department was available to comment.