A survey of 11 secondary schools in different authorities by the Headteachers' Association of Scotland has found little consistency in the way money is allocated, even in schools of similar size and type.
The association says that as a result schools are also struggling to meet the priorities laid down by the Scottish Executive - including its discipline strategy, the success of which varies considerably, according to an HMIE report this week (page four).
Lindsay Roy, the HAS president, told The TES Scotland: "All schools now have expectations that they will continuously improve under the Executive's national priorities. It should therefore be a legitimate expectation that all schools should have equitable levels of funding and that the mechanism for allocating funds should be fair and transparent."
The association stops short of recommending direct funding from the Executive, but it does hope that the audit of schools being carried out by HMIE and the Accounts Commission in relation to the implementation of the teachers' agreement will expose the shortcomings in the system.
"Despite HAS having raised these issues over several years, there has been no apparent move towards a more consistent resource allocation model across the country based on a clear set of criteria," it said in a statement today (Friday).
It continued: "The Scottish Executive should therefore be discussing this issue with local authorities as a matter of urgency. The funding disparities revealed give major cause for concern.
"It is of even greater concern that there are wide disparities in the allocation to schools of funds which the Executive has targeted for specific educational purposes."
In the 11 secondaries studied, the best resourced works on a devolved budget of pound;3,513.77 per pupil, while the lowest gets by on pound;2,666.28. This gap amounts to an annual budget of more than pound;500,000, or the equivalent of 16 full-time teachers.
The two schools have the same roll, although they do differ in terms of the "poverty index" of free school meal entitlement (FME). There were more than 30 per cent of pupils on FME in the case of the highest funded and from zero to 10 per cent for the other.
However, there was no firm consistency in funding even for schools with the same FME. If the most generously funded school was removed from the equation, there was no direct correlation among the remaining 10. The schools ranked second, third, fourth and eighth in terms of funding all have an FME of around 20 per cent. The cash difference between the second and eighth school, with the same FME, is around pound;250,000 - the equivalent of 6.5 full-time teaching posts.
The HAS survey shows little connection between schools with a low FME either. Two schools with the same roll of 1,000-1,050 pupils vary by pound;207.32 per pupil, which amounts to a funding gap of pound;250,000.
Funding for the national priorities ranges from pound;98.03 per pupil to pound;22.47. The figures include:
* Continuing professional developmentstaff development - pound;41.31 to Pounds 7.48 per pupil, a difference of nearly pound;32,000.
* Higher Still - pound;12.89 to pound;4.35 per pupil.
* Enterprise education - pound;11.83 to pound;3.09.
* Study support - pound;40.67 to pound;4.34.
* Discipline - pound;31.29 to pound;2.12 (for a school with one of the highest FMEs of 20-30 per cent).
Heads say these problems are exacerbated by the system of cash targets for devolved budgets which forces schools to make savings. Six of the 11 schools in the survey were in that position. "These savings in effect reduce the number of staff the schools can employ, as the cash targets are so large that this money can only be saved from staffing," they say.
There are other constraints: only five of the schools have freedom to transfer money between budget headings, with varying restrictions for the other six.