The whole UC idea is technically a good one in that it is supposed to link to HMRC to determine the earnings of a claimant (if any) and adjust benefit payment accordingly such that people are always better off working than not.
The fact that the various civil service departments are completely incoherent in their IT systems is a major issue for the roll out of such a system and is the main thing that should have been sorted prior to the introduction of UC.
How many of you El Reg readers have had letters through from HMRC regarding child tax credits etc and asking you to tell them you and your partners earnings - they have your NI numbers etc, why the hell can't they just look it up??
By having a real-time link between systems (or even better, a single system) then the roll-out of any such link to benefits would be much simpler.