Central government is not monitoring how Payment By Results schemes are operating, the National Audit Office (NAO) has warned.

According to a new report published by the watchdog today, Payment by Results now accounts for at least £15bn of public spending and the schemes are being used in a variety of areas, including welfare to work, offender rehabilitation and family support.

But the report warns that Payment By Results is not suited to all public services and commissioners have often failed to explain why they have chosen it as a delivery mechanism.