Tax classification change allows refund of wrongly paid CGST/SGST after IGST payment, subject to prescribed refund conditions. If a supply originally treated as intra state results in CGST/SGST having been paid but is later held to be inter state, the taxable person, upon payment of IGST, may claim a refund of the CGST/SGST paid; the refund is subject to statutory refund conditions and additional prescribed conditions and procedural requirements.