At present, the transfer of input tax mainly includes the following situations: (1) abnormal losses of taxpayers' purchased goods, in-process products and finished products; (2) Goods or taxable services purchased by taxpayers are changed in use, such as non-taxable items, tax-free items or collective welfare and personal consumption. In these two cases, because the original purchased goods or taxable services can not produce VAT output tax, the deducted input tax has lost its source of deduction, and it has to be transferred out.