Section 16 of IGST Act defines Zero rated supply as follows:

(1) “zero rated supply” means any of the following supplies of goods or services or both, namely:––
(a) export of goods or services or both; or
(b) supply of goods or services or both to a Special Economic Zone developer or a Special Economic Zone unit.

(2) Subject to the provisions of sub-section (5) of section 17 of the Central Goods and Services Tax Act, credit of input tax may be availed for making zero-rated supplies, notwithstanding that such supply may be an exempt supply.

(3) A registered person making zero rated supply shall be eligible to claim refund under either of the following options, namely:––
(a) he may supply goods or services or both under bond or Letter of Undertaking, subject to such conditions, safeguards and procedure as may be prescribed, without payment of integrated tax and claim refund of unutilised input tax credit; or
(b) he may supply goods or services or both, subject to such conditions, safeguards and procedure as may be prescribed, on payment of integrated tax and claim refund of such tax paid on goods or services or both supplied, in accordance with the provisions of section 54 of the Central Goods and Services Tax Act or the rules made thereunder.