Section 142(9)(b) in The Central Goods and Services Tax Act, 2017
(b)where any return, furnished under the existing law, is revised after the appointed day but within the time limit specified for such revision under the existing law and if, pursuant to such revision, any amount is found to be refundable or CENVAT credit is found to be admissible to any taxable person, the same shall be refunded to him in cash under the existing law, notwithstanding anything to the contrary contained in the said law other than the provisions of sub-section (2) of section 11B of the Central Excise Act, 1944 and the amount rejected, if any, shall not be admissible as input tax credit under this Act.