Section 54(3) of the CGST Act, 2017 reads as follows:
"Subject to the provisions of sub-section (10), a registered person may claim refund of any unutilised input tax credit at the end of any tax period:
Provided that no refund of unutilised input tax credit shall be allowed in cases other than––
(i) zero rated supplies made without payment of tax;
(ii) where the credit has accumulated on account of rate of tax on inputs being higher than the rate of tax on output supplies (other than nil rated or fully exempt supplies), except supplies of goods or services or both as may be notified by the Government on the recommendations of the Council:
Provided also that no refund of input tax credit shall be allowed, if the supplier of goods or services or both avails of drawback in respect of central tax or claims refund of the integrated tax paid on such supplies."
These are ex facie views of mine and the same should not be construed as professional advice / suggestion.