Mandatory

HSN code may be declared only for those inward supplies whose value independently accounts for 10% or more of the total value of inward supplies;
https://www.cbic.gov.in/resources//htdocs-cbec/press-release/22181222_Press%20Release_31st%20GST%20Council%20Policy.pdf;jsessionid=57ADE503A3A7E2306FDF55BD834652DE

Recommendations made during 31stMeeting of the GST Council