A taxing problem for single-issue campaigners

By the age of 16, Sacha Corcoran was pregnant and homeless. She has two children by two different fathers and has had to endure a string of menial jobs to make ends meet.

But today, at 39, she has a degree, is earning £55,000 a year as a senior manager at a further education college and her children are happy and successful. Her son, Ricky, 21, has just graduated from university and her daughter Saffron, 13, will soon start studying for GCSEs.

Ms Corcoran is furious with David Cameron for his plans to give married couples a tax break. "I think it's blatant discrimination," she says. "I feel that the policy is based more on his own moral views rather than what is best for the people involved.

"Lone parents are portrayed as people who do not work or have careers or pay tax. In fact, many of us do work full-time in very demanding careers. For me to have to pay more tax than a married colleague would be blatant discrimination. My children would benefit from a tax break just as much as theirs would.

"I do not think being married makes a family. What makes a family is having one or two very loving parents who take responsibility for their children."

The issue of marriage became a key ideological battlefield in British politics after Mr Cameron pledged that the Conservative Party would, if elected, "celebrate" and "encourage" marriage. He accused Labour of a "pathological inability to recognise that marriage is a good thing", elaborating: "I think marriage is a good institution... which helps people stay together, and commit together. A society that values marriages is a good and strong society.

"I don't need an opinion poll to tell me whether it is or it isn't. That's just what I think."

The Tories link family breakdown with poverty and crime, and say a loophole in Labour's tax system means some couples are financially better off if they separate. So, when the long-awaited tax break for married couples was finally unveiled this month as worth up to £150 a year and just for some couples, critics queued up.

The amount was peanuts, some said, and hardly an incentive to couples to stay together; it would cost the Exchequer £550m when the national deficit is £167bn; and what's more, the state has no right to exercise "moral authoritarianism" over private lives.

Mr Cameron's promise will allow up to £750 of the income tax personal allowance to be transferred between adults who are married or in a civil partnership, so long as the higher-income member of the couple is a basic-rate taxpayer. The only people to gain from this policy are couples in marriages or civil partnerships where just one member pays income tax and where the personal income of the taxpayer is less than £43,955. An estimated four million married couples (out of Britain's total of 12.3 million married couples) will be better off.

The policy is not, therefore, a general recognition of marriage in the tax system, because it affects only one in three married couples. About 1.5 million of the benefiting couples will be married pensioners.

The independent Institute for Fiscal Studies (IFS) – whose figures the Tories used to justify their plan – questioned whether the proposals would change people's behaviour. "The incentives to marry – or not to divorce – provided by a policy whose maximum benefit is £150 a year must surely be weak relative to the other costs and benefits involved," it said.

And the IFS questioned the decision not to target the tax breaks at families with young children. "If encouraging marriage is seen as desirable primarily for the impact that it has on child development, it is not clear that a policy where pensioner families make up more than a third of the beneficiaries is well-targeted."

Labour condemned Mr Cameron's announcement as "social engineering" and Nick Clegg dismissed it as "patronising drivel", saying people married for love, not £3 a week.

The Lib Dems condemn the Tory plan, saying it "takes money out of the pockets of the poorest families and gives it to rich ones". But their own family policy has been very low-key. They pledged to introduce 19 months of paid parental leave and offer parents free childcare for all children between 18 months and five years. Critics question the affordablity.

The Conservatives claim Labour has undermined marriage by focusing too narrowly on the welfare of children and as a result have neglected the importance of the family. A Conservative paper, Making Britain More Family Friendly, argues that "the warmth of their parenting is as important to a child's life chances as the wealth of their upbringing", and promised to help promote "strong and secure families".

The Government's former child poverty tsar, Lisa Harker, recently conceded that Labour's record on the family was "long on policy and very short on narrative". She added: "For many years it has been impossible to describe Labour's family policy apart from describing a list of initiatives. In my view, none of the political parties have a clear and comprehensive take on family policy.

"In Labour's case... ministers and civil servants struggled to articulate a vision. They were very fearful of appearing to favour one family form over another. Under Labour, the solution has been to launch 1,000 initiatives. This has been laudable and has changed life for the better for many families but it is a bit of a sticking-plaster solution. Something more fundamental is needed."

Tax breaks for married couples reached Mr Cameron's desk in part because of arguments put forward by the Centre for Social Justice (CSJ), the thinktank of Iain Duncan Smith which has influenced Conservative social policy. The CSJ's own research concluded that "if you don't grow up in a two-parent family you are 75 per cent more likely to fail educationally, 70 per cent more likely to become addicted to drugs, and 50 per cent more likely to have an alcohol problem".

It concluded: "Marriage is not a silver bullet, but combined with early intervention, reform of the benefits system, and general couple support, it plays a crucial role in tackling social breakdown." The Conservative shadow Families minister, Maria Miller, insists that the Tories "do not want to go back to any 1950s ideals of family life".

But many thinktanks and lobby groups dispute the interpretation of the research adopted by the CSJ and the Tories. Dr Katherine Rake, head of the Family and Parenting Institute, said: "There is no evidence that this kind of tax break will do anything to incentivise people to get married or stay married. It's also very expensive. If we are going to invest billions of pounds in tax breaks then shouldn't we be sure it's going to work?"

Fiona Weir, chief executive of Gingerbread, the single parents' charity, said the discussion of Tory tax breaks for married couples has been demoralising for single parents and their children. "Some of the debate has been expressed in extraordinarily stigmatising language, broken homes, feral kids, feckless parents," she said. "David Cameron tries very hard to avoid stigmatising language and we recognise and appreciate this.

"But when he talks about tax breaks for married couples it makes our members feel like second-class families because it is rewarding marriage as the gold standard. They do not see why someone should get more money simply because they are married."

All parties agree that preventing relationship breakdown is a key part of family policy. The election battleground will be over how the state should intervene, and how much of a difference any Government can make.