method/step 1 connect the computer to the golden tax plate and log in to the "billing software". 2 Select "System Settings". 3 Select "Commodity Code". 4 Click "Add" to enter the "Add Commodity Code" interface. 5 Enter the tax code of duty-free goods, select Yes in Enjoy Preferential Policy and Tax Exemption in Preferential Policy Type, and the Tax Rate will be automatically set to Tax Exemption. 6 Click "Save" after review.