Child Benefit (CB) is blunt and paid indiscrimiately to all families. It is however cheap to administrate as a result. Family Tax Credit (FTC) is targeted at poorest. Of course, that makes it very expensive to administer.
Combine to a single benefit targeted at the poorest – those below 1.5x average income through Tax Credit system. Benefits scalled to benefit the lowest income families.
Why is this idea important?
The cost of the benefit would be substantially less than the current two benefits combined.
The administrative costs would be greatly reduced – none for CB and greatly reduced for FTC as fewer people would quality.
Poorest woule receive a bit more than is currently the case.