Social breakdown 'is costing Britain £102bn every year'

The party's review group on social policy will put a massive price on the effects crime, poor education and family break-ups have on the economy.

The long-awaited findings of the taskforce led by former Tory leader Iain Duncan Smith are tipped to inspire the first planks of the party's next manifesto.

Mr Duncan Smith's interim report in December was widely hailed as a definitive piece of work on a neglected area of policy.

It prompted David Cameron to confirm that tax cuts for couples are part of the Tory agenda and will be used to shift the balance of state support in favour of families.

It is understood that the social justice policy commission used Government statistics to cost the overall impact of social breakdown at £102billion a year.

The total is made up of £24billion for family breakdown, £18billion for educational under-achievement and £60billion for crime.

Six months ago Mr Duncan Smith and his taskforce warned that family breakdown and debt are out of control.

Mr Cameron has already promised to overhaul the tax and benefit system to recognise marriage and reverse Labour policies which encourage couples to earn more benefit by living apart.

The Tory leader said he would "set a simple test for each and every one of our policies - does it help families?"

The interim report recorded clear evidence that cohabiting couples were more than twice as likely to break up as married couples.

It found that three-quarters of family breakdowns affecting young children involve unmarried parents.

It also warned that a national debt crisis is causing misery for millions and fuelling family disintegration.

Personal borrowing has reached a total of £1.25trillion - meaning each household owes an average of £50,000.

The study said family breakdown is happening at a greater rate than ever before and is costing the country more than £20billion a year.

Mr Cameron has raised the possibility of a transferable tax allowance which a parent who chooses to stay at home could pass on to their working partner.

But he is also under pressure to tackle the bias in the benefits system that effectively encourages families to live apart in order to claim more from the state.

Mr Duncan Smith's report, which is expected out next week, is likely to make substantial recommendations in this area which could carry heavy cost implications for the Conservatives.

He has been pressing his party to champion the family by giving it recognition in both the tax and the benefit system.

The issue is likely to dominate the public policy debate in the run-up to the next election.

Gordon Brown signalled his determination to fight the Tories on family issues by appointing his closest adviser Ed Balls to head the new Department for Children, Schools and Families.

Mr Cameron replied by appointing rising star Michael Gove to shadow Mr Balls.

Mr Duncan Smith's interim report - called Breakdown Britain - also paved the way for a crackdown on major lenders, which are accused of handing out loans and credit cards like confetti to unsuitable customers.

It found that 12million Britons are suffering from serious debt problems - twice the official estimate.

His group has consulted more than 800 experts and organisations in preparing its final report.