Reversal of input tax credit: pro rata apportionment for stock and capital goods with prescribed reporting and certification. Reversal of input tax credit requires pro rata apportionment for inputs and inputs contained in stock using original invoices, or market valuation if invoices are unavailable, and pro rata computation for capital goods based on a five year useful life. Credits must be determined separately for integrated and central tax, included in output tax liability, reported in prescribed GST forms, and estimates certified by a practicing chartered or cost accountant.