A total of £1.2 million paid by developers and intended for community projects was left unspent by Essex County Council in the last five years, it has emerged.
The money, which could have been spent to improve people's lives, was handed back to developers.
It the largest amount handed back to developers by any of the 316 local authorities in England which responded to a freedom of information request by the BBC.
The money was given to the council under Section 106 agreements which are applied as a condition of planning approval.
Possible uses for the money include building affordable housing or improving roads, parks and youth services.
John Jowers, cabinet member for libraries, communities and planning at the county council, told the BBC: "We try as far as possible not to return contributions but we acknowledge that there are circumstances in which returns are inevitable."
Mr Jowers explained reasons for returning the money included the agreed timeframes for spending elapsing, the funding exceeded the cost of a specific project or the infrastructure earmarked for investment being no longer needed.
In total the authority received more than £36m in contributions in the same period.