I had come across in the FCOM that there is no anti ice system for the vertical and horizontal stabilisers while looking at the schematic diagram. I find it very strange that the other surfaces on the empennage do not have anti-ice systems.
On PPrune I found:
The aircraft has been designed to account for that. (Simplistically, the tail is over-sized to compensate for reduced effectiveness when ice forms; it's easier/cheaper/simpler to make the tail a bit bigger and take a weight penalty than to install a whole extra anti-icing system on the tail, which is why that's the typical approach for higher speed aircraft)
To me this makes sense, as the weight penalty for making the tail a bit larger is not as big as the weight penalty for making the wing a bit larger.
Another thing that is different between wings and empennage is ice build up on the wing near the engine could suddenly let go and end up in the engine and cause damage. To prevent the ice buildup, anti icing is used. On the empennage this is no issue.