The Central Board of Indirect Taxes and Customs (CBIC) has made it mandatory to mention the 8 digit HSN code in tax invoices for 49 chemical-based products while issuing GST invoice. The move is expected to reduce tax evasion. HSN or Harmonized System of Nomenclature code is a system for classification of goods across the world. This classification is used to help with taxation i.e. helps identify which tax rate is applicable to a product.