Section 133(3)(b) in Kerala Goods and Services Tax Rules, 2017
(b)return to the recipient, an amount equivalent to the amount not passed on by way of commensurate reduction in prices along with interest at the rate of eighteen per cent from the date of collection of higher amount till the date of return of such amount or recovery of the amount including interest not returned, as the case may be, in case the eligible person does not claim return of the amount or is not identifiable, and depositing the same in the Fund referred to in section 57;