Many schools which chose to convert to academy status last year were mistakenly given extra public funding, in some cases worth tens of thousands of pounds, it has been reported.
The Financial Times said an average secondary school, teaching 1,000 pupils, which converted to an academy at the start of 2010/11, would have received an extra £118,000, while others may have received more than £300,000. It said the overpayments had been caused by officials using old and inconsistent data to work out funding.
Academy schools were originally set up under Tony Blair's Labour government and were aimed at boosting standards in the poorest areas.
Last year, Education Secretary Michael Gove announced plans to open up the academies scheme to allow all schools to apply. In total, 842 schools converted in 2010/11, allowing them greater freedoms over areas such as pay and conditions and the curriculum, although they are meant to be funded at the same level as local authority schools.
Academies receive their funding directly, and this is supposed to include the money for services which local councils provide to other schools, known as the "local authority central services equivalent grant".
The Financial Times reported that it was this figure which was worked out based on old spending data which led to overpayments.
The newspaper's analysis suggests that in 74 boroughs in 2010/11 overfunding was worth over £100,000 over the course of a year for an average 1,000 pupil secondary school, while in 28 boroughs it was more than £200,000 and in 10 it was over £300,000.
It also reported that rules designed to stop schools' funding dropping too quickly from year to year could mean that 790 academies could receive extra money in 2011/12. It is not thought that every school which converted to become an academy was given overpayments.
A Department for Education spokesman said: "Academies receive similar per pupil funding for teaching and an extra grant to pay for the services no longer supplied by their Local Authority. These extra amounts are calculated using a system in place for many years.
"However, the Government has been very clear that the current system is flawed. That is why we made immediate changes to the formula last year, and have since had detailed discussions with local authorities on how to make the system fair and transparent in the future. We expect to announce further improvements shortly."