I respectfully differ with Ms. Charu Tyagi Ji for her post at Serial No. 17.
Relevant position from Section 54 (3) 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:
................................"
First, ITC itself is not available in subject scenarios under discussion here (unless and until one is thinking of challenging the validity of above quoted Rule 43 (1) in view of wordings of Section 17 (1) & 17 (2) which will be very aggressive view and which is definitely against intention of Govt. & entire ITC philosophy) which is not falling under zero-rated supplies. Hence, question of refund of non-existent ITC does not arise.
Even otherwise, above quoted Section 53 (3) specifically denies refund of accumulated ITC against 'output supplies which are nil rated or fully exempt supplies'.
Note: As a matter of fact, wordings of said Section 53 (3) (ii) gives further support to the argument challenging validity of rule 42 & 43 which denies ITC against goods / services used exclusively for effecting exempt supplies. But, that is matter for a separate debate.
These are ex facie views of mine and the same should not be construed as professional advice / suggestion.