Can anyone tell me what "cannot legally be occupied" means when deciding if a property can be exempted from council tax indefinitely? My client cannot live in his property because it is undergoing major renovations after a disaster. It does not have any utilities. The year's exemption has expired and the work is taking much longer than expected through no fault of the client. He is already receiving full CTB for another property where he is living.
The example given in CPAG is where there is a compulsory purchase order on a property, but could this definition apply where e.g. Environmental Health could prevent him from occupying the house? Any law I could quote?

Your client could go to the Valuation Office Agency and ask for the property to be taken out of the Council Tax List for the duration of the renovation. (Go here http://www.voa.gov.uk/ to find the right VOA office and ring them and ask for a Council Tax Appeal Form.)

Thanks for that. He has tried that but the visitor from the valuation office told him as soon as she stepped inside the building that he would not succeed. I will look further into exactly when this happened and if he received a letter explaining the decision. Would he have the right to appeal such a decision?

I'm not sure about appeal. Correspondence received fom the VOA should tell him this - or give them a ring.