Yes, one of the cases can be incentives/ rebate received from supplier which is considered as a supply under GST. Incentives/ rebate received from the supplier can amount to a taxable supply under the GST. Where the taxable person has reduced the incentive/ rebate received from the cost of purchase in the books of accounts, the said amount will be added under Sl. No. 5O so as to reconcile with value declared in FORM GSTR- 9.