Assesses council tax (5)
I believe the answer is:
rates
I believe this is a double definition.
'assesses' is the first definition.
(rating is a kind of assessing)
'council tax' is the second definition.
(I've seen this before)
(Other definitions for rates that I've seen before include "Stare (anag.)" , "Local taxes on commercial property" , "Former means of local revenue" , "Evaluates the importance (of something)" , "List of charges" .)