The Collaborative International Dictionary of English v.0.48:

Taxer \Tax"er\, n.
   1. One who taxes.
      [1913 Webster]

   2. One of two officers chosen yearly to regulate the assize
      of bread, and to see the true gauge of weights and
      measures is observed. [Camb. Univ., Eng.] [Written also
      taxor.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

taxer
    n 1: a bureaucrat who levies taxes