By Gary Eason
Education editor, BBC News website
Head teachers must wait to see how much they will receive of the extra direct funding the Chancellor promised them.
Some schools need "extra" money to replace discontinued funding
Gordon Brown said a typical secondary school would get a total of £190,000 in 2007-08 - twice the present figure.
He also said they would get £52,000 more "from next week".
The extra for a typical primary school is said to be £8,500 more from next week and another £4,500 more next April, taking the total for 2007-08 to £44,000.
The Department for Education has said that, in fact, schools should expect the 2006-07 money in September.
It will not be shared evenly. And a head teachers' leader has said there is growing concern at wide disparities between schools.
Gordon Brown described it as money going "direct to the head teacher".
In practice, like most funding, it actually goes via local authorities but is "ring-fenced" so they have to pass it on to schools.
So it is different from the biggest block of funding which is based on a formula and which authorities carve up between the schools in their area.
In years gone by Mr Brown liked to describe the "direct" funding - known as the School Standards Grant - as money heads could spend "as they wished" on their own priorities.
That was not a phrase he used in this latest Budget.
There are probably two reasons for this.
One is that the extra money this year is intended specifically for one policy: "personalisation".
This means such things as one-to-one or small-group tuition, and catch-up classes for slower learners.
The other reason is it will not be allocated evenly.
"The new money will be paid on a different basis to the rest of School Standards Grant, which is based largely on pupil numbers," the Department for Education and Skills says.
"A significant proportion of the new money for personalisation will be targeted towards schools with low prior attainment and high levels of deprivation."
This worries the general secretary of the National Association of Head Teachers, Mick Brookes.
All schools get a basic amount per pupil, which is then added to - notably to take account of local deprivation and pupils' ethnicity, along with money targeted on urban areas "and a whole heap of other funding that comes on top of that".
"Labour has put its money where its mouth is, which is good, but there's an issue now with that," he said.
His union has been doing some calculations on the variations in funding.
Mr Brookes said the gap between the average lowest-funded schools and the average highest was some £320,000 a year for primary schools and £2m for secondaries.
There were also "very large disparities" between different schools within authority areas.
On the School Standards Grant, he said it was likely some heads would get quite a lot more money but others "not much at all".
"Some heads say they have so much money they don't know what to do with it," he said.
Others were so "strapped for cash" they were having to cut the number of teaching assistants they employed.
Union leaders are expecting to be briefed next week by the Department for Education and Skills on the implications of this year's funding announcements.
The department says it plans to publish detailed guidance to local authorities before Easter.
For Mr Brown's new "personalisation" money, it aims to provide a "ready-reckoner" on the TeacherNet website by Easter so schools can work out what their allocation for 2006-07 will be.
Changes to funding streams mean schools might need some of the "extra" just to maintain existing levels.
Clarissa Williams, head of Tolworth Girls' School in Surbiton, Surrey, said she expected to get £50,000 or £60,000 more than this year.
"It will probably allow me to put a little more into purchase of IT equipment - which in fact we had seen reducing because the grant that we had had for that in previous years had been reduced," she said.
"So in a sense all that that will do is reinstate the amount that we would like and will now be able to spend."
The government is also changing the way schools' performances are assessed.
Already the inspectorate in England, Ofsted, is making judgements based on a new "contextual value added" formula.
This is meant to measure how much progress children have made, taking into account factors outside a school's control - such as local poverty levels and children's ethnicity.
Some head teachers are unhappy that it takes no account of funding differences.
They say it is unfair that schools get extra money to teach children who might not do well - and are then given extra leeway for having those children.