Dear Suresh Yadav ji
The Supremacy of Section 16(1)(b).
In my understanding your reply has ignored the second limb of Zero-Rated supplies. Under Section 16(1) of the IGST Act, "zero-rated supply" means any of the following supplies of goods or services, namely:
1. Export of goods or services; OR
2. Supply of goods or services to a Special Economic Zone developer or a Special Economic Zone unit.
The Fact:
Even if the transaction does not meet the definition of "Export" under Section 2(5) (because the goods don't leave India), it indisputably qualifies as a Zero-Rated supply under Section 16(1)(b) because the goods are delivered to an SEZ unit.
The CBIC has already clarified the "Bill-to/Ship-to" mechanics. In a scenario where the "Bill-to" party is located outside India and the "Ship-to" party is an SEZ unit: The supplier (Domestic) issues an invoice to the Foreign Entity. The goods move to the SEZ unit.
The logic that delivery to an SEZ is not "Zero-Rated" simply because it doesn't qualify as an "Export" is a misinterpretation of Section 16. The IGST Act provides two independent pathways for Zero-Rating. The delivery to an SEZ unit is a deemed inter-state supply and is eligible for all zero-rated benefits, regardless of the billing address or the technical "Place of Supply" definition in Section 10.
Conclusion:
Since the goods are consumed within the SEZ for authorized operations, the supplier is entitled to claim the benefit of Zero-Rating (either under LUT or on payment of IGST).