How to report negative value in HSN-wise summary if credit note value is higher than invoice value?

Table 9 needs these Amendments to outward supplies that are taxable and reported in table 4,5 & 6 of the earlier tax periods’ GSTR-1 return (including debit notes, credit notes, refund vouchers issued during the current period)

Table 7 for interstate supplies. But this input tax claim is not mwntiined very cleary on the net.

I also have a doubt about the question,  if you have sales return for 10 lakhs previous period filed and 2 laks, i believe you can adjustments to 8 laks and provide the infomation while filing. 

The GST portal does not allow negative values in the HSN-wise summary (Table 12). Credit notes must be correctly reported in Table 9, and any resulting negative net balance for an HSN code in Table 12 should be capped at Zero ($0$) or adjusted as per current portal validation rules to prevent filing errors.