we need to automatically calculate tax base on tax classification code in E business in AR auto invo

we need to automatically calculate tax base on tax classification code in E business in AR auto invoice, Data is loaded into RA_INTERFACE_LINES_ALL currently we are using TAX_RATE,TAX_CODE column to enter tax code but system is not generating automatic tax line on the base of code , if we create a manual transaction in AR and enter tax classification code then system is working fine. please guide us to generate automatically calculated tax line on the basis of tax code use