Plans to redress differences in school funding across England are expected to be outlined in the Autumn Statement.
Change will begin in 2017-18 after consultation on the details, which could happen in early 2016, George Osborne is likely to say on Wednesday.
This would begin to reduce historical variations in funding per pupil between different areas of England.
School budgets face a likely fall of 8% per pupil due to rising costs during the next five years.
Against that background ministers have accepted that funding differences which have accumulated over decades need to be addressed.
Two weeks ago Education Minister Sam Gymiah told MPs: “It is patently unfair that Knowsley received nearly 750 less per pupil than Wandsworth.”
More pupils in the deprived borough in the north west of England are entitled to free school meals than in the wealthy London borough.
Graham Stuart MP, one of the vice-chairs for the f40 campaign which has lobbied for change, said he was delighted by a firmer policy commitment.
He said the details would be crucial, including how exactly fair funding would be calculated, how much money would be moved, and at what speed.
“You’re talking about redistribution, which is easier to implement at a time of rising budgets,” he said.
“But the case for change is more important than ever at a time when budgets are not increasing.”
The Association of School and College Leaders (ASCL) says that in the current financial year the gap between the best and worst funded schools in England is 1.9m.
Brian Lightman, ASCL’s general secretary, said he was very pleased the government seemed to be committed to fair funding.
“The key issue will be to make sure the plans are modelled thoroughly over a realistic timeframe, to make sure schools can maintain the quality of education during change,” he said.
There will be winners and losers in any change.
London boroughs are likely to be among those that will lose out.
The pupil premium funding for children entitled to receive school meals will remain in place throughout this Parliament.
The value could fall in real terms over the Parliament, but it will continue to provide additional funding in areas with more children from low income families.
After several years of being sheltered from the public spending squeeze, schools are now under financial pressure.
Both National Insurance and teacher pension contributions are going up, reducing the money schools have to spend per pupil.
Overall the public spending review could bring mixed news for education.
Funding for 16 to 19 year olds is not protected under Mr Osborne’s plans and fell during the last Parliament.
This has put both sixth-form colleges and further education colleges under considerable financial pressure.
Spending on early years is vulnerable too, despite a commitment to increase the free childcare for working parents to 30 hours.
It is possible these will not be funded at the same level of staffing as the existing 15 hours offered to parents in England.
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