Or Scotland will need to extend means- testing up the income distribution, so that families above the UC cut-off are still eligible, which will significantly increase administration costs and mean a whole lot more families need to report on their incomes and on income changes. The history of the UK’s child tax credit system, which effectively brought 90% of families with children into means-testing, is interesting in this regard: it is possible to make this work and the system improved significantly over time, but there were considerable teething difficulties.