This paper reflects on the impact of a decade of austerity measures on children in the UK, with a particular focus on the growing emphasis on cost benefit analysis (CBA) as a public rationing device. The argument points to the dangers of the now widespread use of this mechanism in the context of resourcing children’s services, not just by state bodies, but by civil society organisations and others charged with the protection of children’s rights. It considers why CBA is so appealing, and points to its potential in creating persuasive economic arguments in favour of investment in children; but it also points to the need for more principled, critical engagement with this device to prevent some of the mischiefs for which it has been used to date. The discussion proposes that a more robust rights-based approach, grounded firmly in the UN Convention on the Rights of the Child, would help to achieve a more fruitful correspondence between economic and children’s rights-related objectives.