i think lots of people will just sign off it and work cash in hand. i already know a few people in my own social circle who are part of a couple and cba with the faff of tax credits (even as they are now,) and do cash in hand work, all sorts, childcare, cleaning, hairdressing
and i also think that couples who have until then relied on tax credits if ones a SAHP and the other one is working but doesn't earn much, well i suspect some of them may well end up "splitting up" and the mum ends up pretending to bea lone parent.
not saying any of its right btw before anyone jumps on me! i just really think it will happen loads more than it does now.