Tory tax breaks for married couples would be funded in part by cutting the benefits of single parents who failed to look for work.

Even single parents whose youngest child is under 5 should spend up to ten hours a week “seeking or preparing” for work to be eligible to receive benefits, according to the Conservatives’ Social Justice Policy Group.

Welcoming the group’s report yesterday, David Cameron, the party leader, gave a clear indication that the next Tory manifesto would include a pledge to give married couples a transferable personal tax allowance worth about £20 a week. “Britain is almost the only country in Europe that does not recognise marriage in the tax system and the benefits system actively discourages parents from living together,” he said.

“We have the highest rate of family breakdown in Europe and we have the worst social problems in Europe. Don’t tell me these things aren’t connected.”

He was speaking after Iain Duncan Smith, chairman of the Social Justice Policy Group, presented a package of measures to address the causes of social breakdown, which he says is costing Britain £102 billion a year. Many of the policies, such as a 7p “treatment tax” on a pint of beer and new parent-run “pioneer schools”, had been made public in advance.

The full details of a clampdown on welfare payments, however, were outlined for the first time. Under the plans, single parents would be required to seek full-time work as soon as their youngest child reached 11, and part-time work from their child’s fifth birthday. Even before their youngest child turned 5, however, single parents would be expected to spend between five and ten hours looking for work or training for a job.

Mr Cameron, who stopped short of any immediate commitments, said that some of the measures, such as reforming the welfare system, would save money. He and Mr Duncan Smith said, however, that the welfare proposals were designed to lift children out of poverty not to save money.

The report says: “Helping more lone parents into work, through both a deliberate shift in expectations and providing support, including childcare as appropriate, will help them and their children in a very real way.” At its launch, Mr Duncan Smith said: “There is nothing in this report that will hurt or damage lone parents at all because we think they have a tough job.”

Critics said that the policies amounted to a return to the “back-to-basics” Conservative agenda and would help middle-class mothers to stay at home with their children while forcing poorer single parents into work. Jane Ahrends, of One Parent Families, said: “This report seems unable to decide whether parents have a right to put their children first: on the one hand it proposes tax allowances to encourage more parents in couples to stay at home to care for children; on the other it wants to take that option away from those who find themselves parenting alone.”

Jenny Watson, chairwoman of the Equal Opportunities Commission, said: “It is good to see the Conservative Party focusing on supporting Britain’s families. But in a Britain where four in ten children are currently born outside marriage, limiting support only to married couples risks penalising children. We believe that support should go to those families who need it most, regardless of whether they are married or not.”

Ed Balls, the new Secretary of State for Children, Families and Schools, said that the Tory plans would harm the most vulnerable children.

Mr Cameron later defended his decision to put marriage at the centre of the political debate, criticising Labour ministers who said that politicians should keep out of the issue. “Are they saying, ‘We do not care if fewer people get married, if more marriages break down, if more families break apart, if more people only have one parent helping bring them up, we do not care about that, it’s just something politicians cannot get involved in at all’?.

“I think that is a complete counsel of despair and a huge mistake and we should be optimistic enough to say that just as in the 1980s we helped to fix a broken economy, today we do not have to accept social breakdown and poverty as just a consequence of a growing economy. We should roll up our sleeves and say we can sort this out if we are prepared to take tough decisions.”

Mr Duncan Smith said that the tax break for marriage, which would also be available to couples in civil partnerships, would cost £3.2 billion. Labour said that the total bill for implementing all 190 of the report’s recommendations could top £10 billion.

Untying the knot

— There were 244,710 weddings in 2005, the lowest since 1896. The marriage rate was 24.2 per 1,000 for men and 21.6 per 1,000 for women that year, the lowest since records began in 1862

— The proportion of married people among the adult population now stands at 50.3 per cent. This compares with 54 per cent in 1997 and more than two thirds in the 1970s

— Sociologists say that the reasons for the decline are numerous. Big divorce settlements in favour of women are said to deter men from getting married, and the number of couples who have witnessed the fallout of their own parents’ divorce is blamed for many others putting it off. The cost of a home, and of the wedding ceremony, are also seen as deterrents

— Labour finally killed off the married couple’s tax allowance seven years ago to help to pay for tax credits, although the Conservatives had let its value wither away so it was worth only a few hundred pounds a year

— The only real financial benefit in being married comes when you are widowed. Husbands and wives can inherit their spouse’s estate without having to pay inheritance tax. Cohabiting couples are liable to pay 40 per cent on all assets above £300,000

— A study of Millennium Cohort Study data on 15,000 mothers who gave birth during 2000 found that 20 per cent of the entire sample had become single by the time their child was 3

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