Cancellation of registration: procedure and input tax credit reversal required when registration is cancelled for prescribed grounds. Section 29 permits the proper officer to cancel registration suo motu or on application for reasons including business discontinuation, change in constitution, loss of liability to be registered, contraventions, prolonged non filing of returns, failure to commence business after voluntary registration, or fraud in obtaining registration; cancellation may be retrospective or prospective but requires an opportunity of being heard. Cancellation does not relieve the person of tax or other obligations for periods before cancellation. Cancellation under the Central Act is treated as cancellation here, and the cancelled registrant must pay, via electronic ledger, an amount equal to input tax credit on stock and capital goods or the output tax on those goods, calculated as prescribed.