The Child Poverty Action Group said it was vital to remember that 400,000 children had a parent on incapacity benefit.
"We welcome any boosts to parental income but what about the most disadvantaged children whose parents are not able to access work - what will they get?" asked Gabrielle Preston, policy and research officer at the group.
The reforms include a pilot, in areas yet to be decided, giving parents with children at secondary school a payment of 20 on top of existing benefits in return for taking steps into work.
A Pathways to Work for Lone Parents pilot in five areas includes childcare help and financial incentives for parents moving into work.
Work and pensions secretary Alan Johnson said helping lone parents return to work was "the best route out of poverty for themselves and their children".
Two new benefits will replace Incapacity Benefit. Rehabilitation Support Allowance and Disability and Sickness Allowance will differentiate between people who have severe conditions and those with more manageable ones.
People with the most severe conditions will automatically receive more money than they do currently, while the majority will be able to top up their basic jobseeker allowance of about 55 a week by taking steps to get back into work.
- www.dwp.gov.uk.
