Some primaries are receiving almost pound;1,000 more per pupil than schools in other council areas, according to new figures showing widening funding variations across Wales.
Although all councils have increased their spending on education this year, they are delegating less cash directly to schools. And several appear to be spending three to five times more on central administration than on school improvement.
The figures emerged as the Westminster Government announced plans to ring-fence school funding in England and give heads three-year budgets so that they can plan effectively.
It already manages closely how English education authorities distribute cash to schools, and far more money is delegated directly to heads than in Wales, where Assembly ministers let local councils make spending decisions.
Headteachers acknowledge that more money is going into education - but say it is not arriving in their schools. Brian Rowlands, secretary of the Secondary Heads' Association in Wales, said: "We welcome the overall increase in education spending. But that doesn't reflect the reality at school level. The best our members are finding are standstill budgets."
He said no progress had been made on reducing the funding gap between the highest and lowest-spending authorities. This year, primary schools in Flintshire can expect to receive pound;2,381 per pupil - compared to a Welsh average of pound;2,700, and a maximum of pound;3,322 in Ceredigion.
For secondary pupils, the range is pound;3,140 (Denbighshire) to pound;3,836 (Ceredigion).
Mr Rowlands called for a national funding formula for schools and noted that the Welsh Assembly had accepted the argument for such a formula for the post-16 sector.
Geraint Davies, secretary of the National Association of Schoolmasters Union of Women Teachers Cymru, said: "The same authorities are around the bottom of the spending table every year, and it's the children who suffer."
Overall, spending on education by Wales's 22 councils, including schools' spending, is set to increase by 5.8 per cent this year (2004-05), according to budget statements submitted to the National Assembly.
But the range of school funding increases this year stretches from 3.2 per cent in Merthyr Tydfil to 12.3 per cent in Conwy. And while local education authorities are not required to delegate a specific percentage to schools, they are retaining more cash than last year, according to David Reynolds of Exeter university.
Professor Reynolds, who has been monitoring council education spending, said: "In every single area, the funding situation in Wales has become more varied."
For example, average spending per pupil on school improvement is pound;79, but ranges from only pound;18 in Powys to pound;168 in Merthyr Tydfil.
That is a ninefold difference compared to only a fivefold one last year, said Professor Reynolds.
A spokesman for Powys council said its school improvement figure was "artificially low", and that some of its spending on school improvement is contained under other budget headings, such as "strategic management".
Sioned Bowen, chair of the Association of Directors of Education in Wales, said it wanted to see if some of the variations between different LEAs arose from such recording "anomalies".
But she added: "Decisions on education spending in Wales are for local determination."
Jane Davidson, education and lifelong learning minister, insisted the funding system had become more transparent with the publication this year of education allocations to LEAs and the introduction of local school budget forums.
She told the Assembly's education committee: "Most areas in Wales are better funded than their neighbours in England."
NEWS 4, LEADER 22, OPINION 23