ITC reversal on stock requires payment of attributable credit and submission of FORM GST ITC-03 within the prescribed period. A person opting for composition levy must pay ITC attributable to stocks held immediately before the option: inputs pro rata by reference to invoices; capital goods prorated by remaining useful life assuming five years with months basis; ITC computed separately for integrated, central and state/UT tax; payment from electronic credit ledger if sufficient or electronic cash ledger, with any remaining credit lapsing. The person must submit FORM GST ITC-03 declaring reversal/payment within sixty days from the commencement of the relevant financial year.