Local authorities must plough more cash into programmes to help ‘troubled families', or face missing ambitious government targets, auditors have warned.

The National Audit Office (NAO) published an assessment of two Whitehall programmes designed to turn around the fortunes of ‘families with multiple challenges' – such as antisocial behaviour and truancy – on 3 December.

While the study recognises that ministers were right to target troubled families, it states that ‘key aspects of performance need to improve if the ambitious targets set by the two departments…are to be met'.

The troubled families unit within the Department for Communities and Local Government (DCLG) introduced a target to ‘turn around' the lives of 120,000 families within three years, while the Department for Work and Pensions aims to move 22% of people in such families towards employment over the same timeframe.

The DCLG's early-intervention programme was deemed crucial after it emerged that the annual cost of troubled families had hit £9bn.

National auditors reported this week that it is ‘too early' to assess the value for money implications of Whitehall's programmes. But they reported ‘there is evidence that families are beginning to benefit' – helped by local authority funding.

However, the NAO also concluded ‘there is a risk that the expectations for the programmes will not be achieved'. Local authorities have already turned around 22,000 families, the report states, but that is 13 per cent below the interim target – an under-performance fuelled in part by poor design of payment-by-results features.

‘Evidence…suggests that local authorities will need to invest further to meet its target,' the auditors warn.

They also claim there is ‘limited evidence' that the DWP's target will be met.   A lack of departmental co-ordination within Whitehall is cited as a problem, leading to ‘overlap' – or waste - within the programmes.

Amyas Morse, head of the NAO, called on Whitehall to ‘intervene' if local authority performances against the targets continue to vary significantly.

Sir Bob Kerslake, DCLG permanent secretary, pointed to last week's government figures suggesting progress against the targets, including children being back at school, youth crime and anti-social behaviour reductions in many areas and parents back at work.

‘These are substantial achievements that are changing lives for the better,' Sir Bob said.