13/03/2012 05:54 GMT | Updated 13/05/2012 06:12 BST

The Poorest Must Not Pay the Heaviest Price

Rachel works 22 hours a week in a pharmacy but after rent, bills and childcare she often has only £10 left for food and other household essentials for her and her two-year old son Luca.

She skips her own meals to be able to give food to Luca, and is constantly worried about money. Rachel has been told she'd be better off on benefits, but she wants to work.

Save the Children supports the government's efforts to make work pay and Universal Credit will do this for many. But our research shows that the scheme has one massive blind spot. There's not enough money to make sure everyone is better off. The government admits that under the proposed changes, 1.1 million families with children will lose out. And single mothers like Rachel will be hit particularly hard - losing up to £68 a week if they choose to work more than 16 hours. Second earners (usually women) will suffer too.

There are already too many children in this country going without basics like proper food or decent clothes. One in three kids in the UK lives in poverty - and perhaps surprisingly, the majority of them are in working households. All too often, there's just not enough money left over once childcare, rent and other bills have been paid. Universal Credit was supposed to change this, but unless the flaw in this otherwise well-designed scheme is fixed, a quarter of a million children will be pushed further into poverty.

The government has promised to help anyone left worse off as a result of the changes - essentially protecting their previous level of payments for a limited period of time. But they haven't said how long this transitional safety net will be in place - nor are they extending it to new claimants. So, sooner or later, poorer working mums will lose out. We think the government should fix the flaw in the scheme now - rather than relying on a retrospective stop-gap.

Every working parent knows it's tough juggling long hours and raising children. It's even tougher if you're on your own. These mums deserve support - not more hardship. If the proposed system is not amended, Rachel and Luca will be around £85 a month worse off. Given how close to the edge they are already, this is a very serious prospect. Rachel told Save the Children that it makes her angry that she'll be punished for wanting to work to feed her child.

Working mums have already seen the worst of the economic crisis. Childcare support has been cut, female unemployment has just topped 1 million, and housing benefits have been taken away from this group. More than half the mums we spoke to told us high childcare costs were the main reason they couldn't work or might have to stop. So working mums were already in the eye of a perfect storm - even before Universal Credit came along.

Universal Credit will help many families - couples in which only one person is earning stand to benefit, as do single mums on fewer hours. But this shouldn't happen at the expense of others. Our new Mums United campaign, which launches today ahead of Mothers Day and the Budget, calls on the government to boost its spending on Universal Credit so that mums working longer hours keep more of their incomes and get support with childcare. (You can sign our petition here).

The reasons for the economic crisis are complex, but one thing is for sure - it's not the children's fault. Fixing the economy will mean making some tough choices, but the poorest must not pay the heaviest price.