By STEVE DOUGHTY

Last updated at 13:26 06 May 2008

Couples with children have to work three times as hard as single mothers to stay above the poverty line, an inquiry has found.

The findings back up claims of bias in Labour's complicated tax and benefits system.

A couple with children on the minimum wage must put in 48 hours of work a week before their income reaches the Government's official poverty line, according to the Joseph Rowntree Foundation.

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Single parents will be among those targeted in a £44m Government scheme which will give them parenting tips via text message and internet

But a single mother can reach the same standard of living with just 16 hours a week on the minimum wage, thanks to the effect of tax credits and other benefits.

The calculations are based on the Government's definition of poverty - households which earn less than 60 per cent of the national median income.

This average figure was calculated as £18,928 last year, meaning families earning £11,357 - £218 a week - after tax and National Insurance are officially living in poverty.

The level is adjusted depending on the number of children in a household.

The report by the foundation presents powerful evidence of bias towards lone parents in the benefits system.

It means that both members of a low-income couple with

young children have little choice but to leave their children with relatives, childminders or in a nursery and go out to work.

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If the mother is determined to stay at home, her partner faces the burden of working 48 hours a week - the maximum allowed under current legislation - to compensate.

Tories say that the system effectively encourages couples to split up.

Not only that, but the tax and benefits penalty for staying together is likely to increase without radical reforms to the welfare system.

In 20 years' time, if it is unchanged and if annual benefit increases continue at the present rate, lowincome couples will have to work an astonishing 72 hours a week between them to beat the poverty trap.

Tory Work and Pensions spokesman Chris Grayling said: "It is nothing short of madness in a country where family breakdown is becoming a real challenge to have a tax and benefits system that actually makes it attractive to live apart.

"If we are going to be serious about tackling family breakdown then this has got to change."

The most recent available figures showed that 200,000 more children have fallen below the official poverty line.

Don Draper, a consultant to the CARE charity, said: "Well over half of all poor children live in couple households - 1.7million of the total of 2.8million. It is the Treasury that is failing these children. Their parents are doing all they can."

He added: "Until the Treasury will accept that it has made a fundamental mistake with the design of tax credits there seems little hope that there can be any long-term reduction in child poverty."

'I was better off before I got married,' says ex-single mum

Sarah Ley: Tight budget even with two parents

Sarah Ley, who has three young children with her husband Adrian, has also experienced life as a single mother.

As a children's entertainer, Mr Ley earns an average of £12,000 a year, but last year he ended up taking home just £8,680.

His wife is a full-time mother to Laurie, nine, Lucie, seven, and Rowan, three. She chooses not to go to work because of the exorbitant cost of hiring a childminder to come to their rural home in Cherry Willingham, Lincolnshire.

The family receive financial help from the Government in the form of £491 a month in child tax credits and £55 a month in working tax credits.

But Mrs Ley, 42, believes the support they now receive is far less than the help she got when she was a single parent.

Before she met Adrian, 39, she was living as a single mother, bringing up her eldest children Leon, now 23, and Letitia, 18.

"I've seen both sides of the coin and I definitely believe that financially it was easier when I was single, because I knew there was this pot of money I could depend on," she said.

"During the summer months, we barely see Adrian because he's always at work."

In the busy periods, Mr Ley works more than 50 hours a week. But his income still cannot pay for foreign holidays for the family.

Mrs Ley added: "We don't drink, don't smoke, and very rarely go out - fundraising for the junior school disco is as good as it gets."