We can *Prove* we have enough money coming in. So they'll just be subtracting the council tax rather then the rent as well? Like I've stated he is on disability benefits.
Well, they subtract both the rent and the council tax from the income, but in your case rent = £0 (or whatever the rent will be after you move in).
I'm not sure what the big deal is though...you just write on the application form what his monthly income is, what his rent is and what the council tax amount for his property is. Then as your evidence, you provide his bank statements, official paperwork from the council detailing his benefits (and that the cover the rent) and maybe a council tax bill detailing his council tax band/amount.
If the property is owned by the council, you will also need written permission from them for you to live in the property as well, along with any changes to rent etc. once you have moved in.