GSTN implements mandatory mentioning of HSN codes in GSTR-1

Vide Notification No. 78/2020 - Central Tax dated 15th October, 2020, it is mandatory for the taxpayers to report minimum 4 digits or 6 digits of HSN Code in Table-12 of GSTR-1 on the basis of their Aggregate Annual Turnover (AATO) in the preceding Financial Year.

source https://www.caclubindia.com/articles/gstn-implements-mandatory-mentioning-of-hsn-codes-in-gstr-1-47490.asp