Registration validity for casual and non-resident taxpayers limited; advance tax deposit and cash ledger utilisation required. Registration for casual and non-resident taxable persons is valid for the period in the application or ninety days from the effective date, with a possible single extension by the proper officer on sufficient cause. Applicants must make an advance deposit of tax equal to estimated liability for the registration period, and any extension requires an additional deposit; deposited amounts are credited to the electronic cash ledger and utilised under the prescribed ledger rules.