The principle of unjust enrichment would be applicable in all cases of refund except in the following cases:-
1. Refund of tax paid on zero-rated supplies of goods or services or both or on inputs or input services used in making such zero-rated supplies
2. Unutilized input tax credit in respect of (i) zero-rated supplies made without payment of tax or, (ii) where the credit has accumulated on account of the rate of tax on inputs being higher than the rate of tax on output supplies
3. Refund of tax paid on a supply which is not provided, either wholly or partially, and for which invoice has not been issued;
4. Refund of tax in pursuance of Section 77 of CGST/SGST Act i.e. tax wrongfully collected and paid to Central Government or State Government
5. If the incidence of tax or interest paid has not been passed on to any other person;
6. Such other class of persons who have borne the incidence of tax as the Government may notify.
In case of any claim of refund to a registered person on account of zero-rated supplies of goods or services or both (other than registered persons as may be notified), 90% refund may be granted on a provisional basis before verification subject to such conditions and restrictions as prescribed in Refund rules in accordance with subsection 6 of section 54 of the CGST/SGST Act.
No, It has been clarified vide Circular No. 18/18/2017-GST dated 16.11.2017 that the restriction on refund of unutilized input tax credit in inverted tax structure is not applicable in zero-rated supplies because the relevant Notification No. 05/2017-Central Tax (Rate) dated 28.06.2017 restricting refund of unutilized input tax credit has been issued under clause (ii) of the proviso to sub-section (3) of Section 54 of the CGST Act, 2017.