Child benefits to families with children over 13 could be scrapped, under a Government-commissioned review headed by new poverty adviser Frank Field.
The Labour MP said he remained opposed to means-testing child benefit but was looking into whether it should be "age-related" or taxed.
Mr Field was appointed by the Prime Minister last week to lead the Review of Poverty and Life Chances, which is tasked with examining what the Government can do to improve the lives of the least advantaged people in society.
Child benefit is currently paid until a child is 19 if they are in full-time education. Parents get £20.30 a week for their eldest child and £13.40 a week for each of their other children.
It costs taxpayers an estimated £11 billion a year.
Mr Field, who served as welfare reform minister briefly under Tony Blair, told the Press Association: "I've always been opposed to means-testing child benefit.
"It's the Government's duty to come up with what it proposes from changes in public expenditure."
He said he was considering a number of options in relation to child benefits.
"One would be to tax child benefit - that has disadvantages," he said.
"One would be to age-relate child benefit - that has disadvantages.
"But means-testing runs counter to one of the objectives of the Government manifesto."
In an interview with The Times, Mr Field suggested that child benefit should be linked more closely to a child's age, with more money provided in the early years.
The benefit could be taken away when the child reached 13 or 14, he said.
"At that age mothers feel even more engaged with work than they are with children," he told the newspaper.
"They feel more secure with their children when they are over 13 and so on. If you have a crisis at work and can't be home, it's not such a disaster as when you have a seven-year-old coming home from school."
A former director of the Child Poverty Action Group, Mr Field was given ministerial rank by Mr Blair in 1997 with a brief to "think the unthinkable" - but was dropped after clashing with Gordon Brown and then social security secretary Harriet Harman over his proposals for radical reform to benefits.
Children's charity Barnardo's warned that any reform of child benefit should ensure that the incomes of poorest families were protected.
A spokeswoman said: "We would be concerned if child benefit was stopped for older children. Nearly four million children, after housing costs, are living in poverty in the UK today.
"Taxing child benefit and ensuring that any surplus is redistributed to the children and families most in need would unarguably be a step in the right direction."Reuse content