FORM RFD-01 is to be filed after:
(a) the person in charge of the conveyance carrying the export goods duly files an export manifest or an export report covering the number and the date of shipping bills or bills of export delivers it under Section 41 of Custom Act 1962; and
(b) the applicant has furnished a valid return in FORM GSTR-3 or FORM GSTR- 3B, as the case may be. Upon the receipt of the information regarding the furnishing of a valid return as mentioned above, the system designated by the Customs shall process the claim for refund and an amount equal to the IGST paid in respect of each shipping bill shall be electronically credited to the bank account of the applicant.
(ICAI FAQ PUBLICATIONS 06-09-2017 REFUNDS: FAQ NO. 23)