Don't forget that this will just be for CTS claims once FS rolls out. Have a think about how much evidence you would want from your client if you can be confident that an overpayment doesn't exist and the 'discount' can just be wiped out and will be recovered from your client.
If you decide that you want evidence of income that you can't obtain from CIS (or you aren't confident of CIS) then you can ask for a screenshot of the client's online journal which will have details of the current award. But for your 'working' UC clients you'll need a new one every month (if your client is paid on a weekly cycle, for example). And if you're reviewing CTS awards every month, think about what that means for your poor CTax team!
What I'm saying is: a) how useful is RBV for CTS only clients? b) it's probably best to trust DWP data while you can still get access to it and c) keep an eye on these forums for LAs who are experimenting with ways of assessing CTS recalcs for UC clients!
