TAXATION MANAGEMENT USING ASYCUDA++ Ó UNCTAD - SITE (V1.15) A.23 Tax Rules in Market Values The  Market  Value  update  screen  has  provision  for  including  a  rule  if  the  normal  functions  fail  to provide sufficient flexibility.  For example if different values are required depending on the country of origin. (See Section 10 of this Reference Document for the ‘Market Value’ function). The Rule is written in MODCHQ, under ‘Functions’, ‘Database Management’, ‘Tariff’, ‘Rule’  and saved.  The  rule  is  ‘Inserted’  by  adding  the  rule  name  in  the   ‘Rule’   field   on   the   Market   Value Update screen. Summary: The Tariff structure is built and calculation of taxes is managed by MODCHQCF and MODCHQ by ·     Creating a taxation column for each tax to be linked to Tariff Commodity Codes; ·     Writing  Taxation  Rules  to  link  to  taxation  columns,  giving  instructions  for  when  and  how  to apply the tax; and ·     Inserting tax rates into the Taxation Columns.