Registration duration limits for casual and non-resident taxable persons require advance tax deposit and electronic cash ledger utilisation. A certificate of registration for casual and non-resident taxable persons is valid only for the period specified in the application or for a limited statutory duration, and supplies may be made only after issuance; the proper officer may grant a further limited extension for sufficient cause. Applicants must deposit in advance an amount equivalent to their estimated tax liability for the registration period, and any extension requires an additional deposit; such deposits are credited to the electronic cash ledger and utilised under the prescribed ledger mechanism.