The Office of the Children's Commissioner has told MPs that a bill to overhaul the child support system represents a lost opportunity.
The Child Support Amendment Bill aims to change how child support is calculated, by taking both parents' income into account rather than just the paying parent.
Parliament's Social Services Select Committee is hearing submissions on the bill.
Deputy Children's Commissioner Jo Cribb said she fully supports making the system fairer and more transparent.
But Dr Cribb said the bill missed an opportunity to focus the child support system on children and to improve the well-being of vulnerable children.