Certificate of registration for casual and non-resident taxpayers requires validity limits and advance tax deposit before making taxable supplies. Registration for casual and non-resident taxable persons requires a certificate of registration valid for the period requested or a shorter statutory period and is a precondition to making taxable supplies; the proper officer may grant a limited extension. Applicants must make an advance deposit of tax equivalent to the estimated liability for the registration period, and additional deposits for any extension; such deposits are credited to the applicant's electronic cash ledger and utilized under the ledger rules.