The 1st Proviso to Rule 46 of CGST Rules 2017 has been amended, vide Notification No.79/2020-CT dated 15-10-2020, for declaration of HSN code in invoice. Under this amended Proviso, Notification No. 78/2020 – Central Tax, dated 15.10.2020 has been issued to make HSN code mandatory up to 4 digits in the B2B invoices with effect from 01.04.2021 issued by taxpayers whose aggregate turnover in the preceding financial year is upto Rs. 5 crores. For the taxpayers whose turnover in the preceding financial year is more than Rs. 5 crores, HSN code is mandatory up to 6 digits in invoices with effect from 01.04.2021.