<h1>Taxpayers Must Declare HSN Codes on Invoices; 4-Digit for Turnover </h1> Taxpayers are required to declare the Harmonised System of Nomenclature (HSN) Code for goods and services on tax invoices as per Notification No. 78/2020, effective from April 1, 2021. For turnovers up to Rs. 5 crores, a 4-digit HSN code is required, while turnovers above Rs. 5 crores require a 6-digit code. Some taxpayers have reported issues with unavailable HSN codes in the GSTR-1 filing system, particularly in table 12, and errors in JSON files. Errors include 'Processed with Error,' 'Duplicate Invoice Number,' and others. Further guidance on resolving these issues is available through a detailed advisory.