Registration validity for casual and non-resident taxpayers requires time-limited certificates and advance tax deposit credited to electronic cash ledger. The certificate of registration for casual and non-resident taxable persons is time limited and must be obtained before making taxable supplies; the proper officer may grant a limited extension. Applicants must make an advance deposit of tax equal to their estimated liability for the registration period, and any extension requires an additional deposit. Deposits are credited to the applicant's electronic cash ledger and utilised under the statutory rules governing ledger use.