This discussion addresses how to claim Input Tax Credit (ITC) on an IGST credit note when there are no corresponding IGST sales for the period. While you can enter the credit note details in GSTR-1, GSTR-3B currently doesn't allow for negative liability entries. Options discussed include amending previous invoices or waiting for future GSTR-3B updates that may accommodate negative values.
Yes option to feed negative value is not available in GSTR-3B, same will be incorporated in 3B within 1-2 months. Till that date you don't have any option.