@ Shriniwas K.
Notification 39/2018-Cental Tax dated 4 September 2018 prescribes GSTR-9 format. In the instructions for filling up GSTR-9A, instructions for Tables 17 & 18 read as below:
Summary of supplies effected and received against a particular HSN code to be reported only in this table. It will be optional for taxpayers having annual turnover upto Rs.1.50 Cr. It will be mandatory to report HSN code at two digits level for taxpayers having annual turnover in the preceding year above Rs. 1.50 Cr but upto Rs.5.00 Cr and at four digits’ level for taxpayers having annual turnover above Rs.5.00 Cr. UQC details to be furnished only for supply of goods. Quantity is to be reported net of returns. Table 12 of FORM GSTR1 may be used for filling up details in Table 17.
Further, it is now understood that for Table 18 (HSNwise summary for inward supplies), reporting of HSN summary is restricted only to those HSN which accounts for at least 10% of the total summary of inward supplies. Probably, there might be some amendment after 4 September 2018.