Cancellation of registration requires reversal of input tax credit and permits retrospective cancellation for specified non-compliance. Section 29 authorises cancellation of registration suo motu or on application for business discontinuance, transfer, change of constitution, cessation of liability or other prescribed grounds, and for contraventions, prolonged non furnishing of returns, failure to commence post voluntary registration, or registrations obtained by fraud, with cancellation effective from any date including retrospectively subject to an opportunity of being heard. Cancellation preserves liability for tax and other dues for periods prior to cancellation, and requires payment equivalent to input tax credit on stock and capital goods or the output tax on such goods, calculated as prescribed.