The HSN-wise summary of outward supplies is the summary of all the goods and services you have sold during a particular filing period. The formula used to calculate it is:
HSN-wise summary of outward supplies = Supplies made to Registered Business + Supplies made to Consumers - (Credit Notes, Debit Notes, and Refund Vouchers created for Registered Business customers + Credit Notes, Debit Notes, and Refund Vouchers created for consumers).
Here, Registered Business and Consumers are the GST treatment of your customers.
and GST filing.