Cancellation of GST registration may be ordered for specified grounds and requires reversal of input tax credits. Section 29 permits cancellation of GST registration for business discontinuance, transfer, change in constitution, prescribed contraventions, prolonged non filing, failure to commence business after voluntary registration, or fraud; the proper officer may cancel with retrospective effect but must provide an opportunity to be heard. Cancellation does not affect liabilities for prior periods and cancellations under the central law are deemed to apply here. A cancelled registrant must debit the electronic credit or cash ledger an amount equivalent to input tax credit on stocks, inputs and capital goods or the output tax on such goods, with prescribed calculation rules and a specified adjustment for capital goods.