^^ yup, if the annex has its own water supply/bathroom/ kitchen it will have its own council tax bill.
Nope, not (fully) true.
We’ve got planning to convert one of our outbuildings into a Granny Annex and one of the conditions is that it is NOT a separate property (and can’t be separately sold). Therefore no separate council tax nor service costs.
Suits us as we were just going to attach it to our services; it does mean that we’ll just go up a band or so (not sure how though).
Not what we were told by our planning/council dept. as the annex has its own kitchen/bathroom/water supply it is classed as seperate living space to our property, ( a living area that could be rented out as a seperate part of the property),so we recieved a seperate council tax charge.
This was challenged and we lost.
Unless different councils take different views, so advice before hand may be prudent.