Dormant money in bank accounts should be used to support voluntary groups and charities fighting social deprivation, a report has argued.
Thousands of bank accounts have not been touched for years
The government is currently looking at ways of putting the estimated £400m in unclaimed bank deposits to better use.
About £250m should be spent on creating a 'social bank' to fund plans to tackle social and financial exclusion, the Commission on Unclaimed Assets said.
But the body said its "first priority" was to ensure people get their cash.
Only then should the remaining money be used to fund a wide range of "social enterprise" projects, it stressed.
Estimates of how much money there is in dormant bank and building society accounts - defined as accounts not used for 10 years - have ranged from £400m to £2.8bn.
Halifax recently launched a campaign to try to reunite its customers with £44m in cash currently sitting in more than 100,000 accounts.
The Treasury, in conjunction with the UK's leading High Street banks, will ultimately have the final say over how any money is distributed although there are already plans in place to invest in youth and community facilities.
The Commission, established in 2005 to examine the issue, said any outstanding money should be used to strengthen voluntary organisations and build a more "cohesive" society.
Its flagship proposal is the creation of an independent Social Investment Bank to provide financial advice and support projects with specific social goals such as community transport or regeneration schemes.
To function effectively, the bank would need start-up funding of £250m and annual income of £20m for at least four years.
The contents of dormant bank accounts would effectively be used as security to finance it, which would still enable account holders to reclaim their money if they chose to.
The Commission said the voluntary sector needed more investment and professional support if it was continue helping disadvantaged sections of society in a way the state and the private sector could not.
Increased tax incentives should be offered to persuade more companies and entrepreneurs to invest in such initiatives.
"A unique opportunity exists to create a new Social Investment Bank to act as a bridge between the social and financial communities," said Sir Ronald Cohen, one of the UK's leading financiers and Commission chairman.
Sir Ronald added that the bank must be able to "leverage its resources with money from private sources and the capital markets and put them to work in our marginalised communities".