Credit notes , gst on credit notes

Deduct credit note taxable value and tax amount in GSTR-3B column 3.1(a), i.e. from outward taxable supplies.

Value of Taxable Supplies = Value of invoices + value of debit notes – value of credit notes + value of advances received for which invoices have not been issued in the same month – value of advances adjusted against invoices

@ Durga Prasad : You should deduct it from Output GST Liability.