As many as 208 local authorities responded to a freedom of information request by the Home Builders Federation (HBF) asking how unspent Section 106 money they have.
Sitting on the cash, which developers must pay to local planning authorities for affordable housing and public amenities, means it has not been invested in roads, schools and healthcare.
It showed the top 20 councils collectively hold around £2bn, with Oxfordshire County Council holding the largest amount of unspent S106 money among all respondents at £287.5m.
And recent committee notes highlight that some of the money has been kept by the county council for more than two decades.
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The notes, published by the county council, highlight “an issue with the age profile of monies held…with some monies having being held for over 20 years without any movement other than accruing of interest”.
The FOI request also asked what purpose the Section 106 agreements were allocated for such as transport, health, education or affordable housing.
Oxfordshire County Council had the largest amount of unspent school and education contributions at £142.60m.
HBF said: “The £142m for schools and educational facilities held by Oxfordshire County Council is by far the largest of any respondent and constitutes around half of the Council’s total unspent contributions.
“These sums are held unspent even though the council has itself admitted that in some parts of the county, such as Banbury and Bicester, some schools were required to create “bulge” classes at short notice and new schools are needed to meet extra demand generated by housing.
“Furthermore, objections raised by local campaign groups and parish councils to new housing developments in Oxfordshire – such as the Hanwell Fields development near Banbury – have highlighted that local schools are oversubscribed or too far away.”
Oxfordshire County Council also had the second-largest amount of unspent highways and roads contributions at £75.9m and the second-largest amount of unspent contributions allocated to healthcare and unspecified purposes at £64.4m.
Neil Jefferson, chief executive at the HBF, said: “With the government desperate to find money to invest in infrastructure to drive growth, it is nonsensical to have billions sat in council bank accounts.
“While appreciating the pressures and constraints on councils, we simply have to find a better way to ensure this money is spent promptly to benefit local communities, support local services and drive growth.”
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Oxfordshire County Council said in a statement: “It is not unusual for Oxfordshire County Council to hold monies in readiness to spend on strategic infrastructure, which often takes many years to be delivered.
“Often infrastructure projects require pooled contributions so that S106 monies are held in order to help fund and deliver the capital programme. Therefore to have an outstanding balance of S106 monies is not out of the ordinary.
“Many of the sites are large and complex and take a number of years to come forward and each will have their own trigger points for S106 payments to be made.
“The county council has an exceptionally good record in negotiating and collecting S106 payments and regularly reviews the quantity of S106 monies held against the infrastructure needed to support or mitigate development.
“This is part of an ongoing review with services.”