Three leading charities have called for income to remain a central component of the way child poverty is measured, ahead of a Government consultation on the issue.
Barnardo's, Save the Children and the Children's Society said they believed low household incomes could reduce a child's life chances.
Barnardo's chief executive Anne Marie Carrie said: "Any debate around how child poverty is measured must have as its focus the life chances of those growing up in hardship right now.
"Money really matters to the poorest families who are often trapped in vicious cycles of debt and torn between impossible choices such as heating their homes or giving hot meals to their children."
Save the Children's chief executive, Justin Forsyth, said: "Ensuring families have decent incomes and improving children's life chances are two sides of the same coin. It is vital that the Government continue to see raising family incomes as an essential part of their drive to help children in poverty realise their potential. For families struggling in poverty, money matters."
The Children's Society's chief executive, Matthew Reed, added: "It is unacceptable that so many children are still living in poverty in modern-day Britain, denied basic necessities like regular food, decent clothing or a warm home. If the Government is serious about tackling disadvantage, income must remain central to how child poverty is identified, recognising that low income severely affects both children's immediate well-being and life-long opportunities.
"It is vital that progress made over the last decade to reduce child poverty is not derailed by efforts to distract attention from the simple fact that having enough money is central to achieving a good childhood."
Work and Pensions Secretary Iain Duncan Smith has said he plans to change the way child poverty is measured, taking into account underlying problems such as worklessness, debt and family breakdown, rather than focusing on income.
A Department for Work and Pensions spokesman said: "Over the last decade vast sums of money have been poured into the benefits system in an attempt to address poverty. This approach has failed with the previous government missing its target to halve child poverty by 2010.
"This Government remains committed to the targets set out in the Child Poverty Act but it is increasingly clear that, whilst money is important, poverty is not about income alone. That is why we are looking to develop better measurements of child poverty which reflect the reality of child poverty in the UK today."