TAXATION MANAGEMENT USING ASYCUDA++ Ó UNCTAD - SITE (V1.15) A.11 Taxation Rules Rates input into taxation column boxes are activated by Taxation Rules. The linking of a Taxation Rule to each column defines ·     When  the  rate  in  that  column  is  applied  (conditions  such  as  for  a  certain  CPC  or  group  of CPC's, like "4" for imports CPC's); ·     Mode of payment of the tax due or to be deferred; ·     The tax base; ·     The tax rate, against the Commodity Code in the tariff or a special rate written into the rule; and ·     The action to be performed The mode of calculation of the tax; The modification of existing taxes (including calculation of loss in revenue); or The deletion of an existing tax. In the example below called Rule "Customs Duty", if the model of declaration is "4" (Entry for Home Use) an action called 'DoTax' is carried out. This action calculates the tax using a combination of data from the declaration and from the System Tariff files. The language of  'Rules' is explained in the section ‘Using Rules’ . Figure A.4: MODCHQCF: Functions: Taxation Standards: National Tariff: Edit Rule In  this  example  the  effect  of  Rule  "Customs  Duty"  is  to  calculate  tax,  at  the  rate  in  the  Customs Duty column against the Commodity Code, on the tax base  ‘StatVal’ (which is calculated from the declaration  data  through  another  Rule).  This  rule  will  then  apply  throughout  the  Tariff  unless exceptions are inserted. For  instance,  exemptions  from  Customs  Duty  can  be  linked  to  specific  procedures,  either  in  the general rules as above, or in specific rules set up at Procedure Code level. See later in this Appendix a full list of Keywords, Functions and Variables used in Tariff Rules. Valuation Note Rules Calculations of Customs value and the apportionment of freight, insurance and other charges are managed by Valuation Note Rules.  Data used in the calculation of Customs value or 'Tax base' is taken  from  both  declaration  input  and  from  other  reference  tables,  such  as  rates  of  currency exchange.   System   calculations   such   as   currency   conversion   and   apportioning   charges   over declaration item lines are handled by Rules.