Summary assessment: expedited power to assess suspected tax liabilities to protect revenue, with deeming and review mechanisms. A proper officer, with prior permission of the Additional or Joint Commissioner, may make a summary assessment and issue an assessment order on evidence of a tax liability where delay would harm revenue; if the taxable person is unascertainable and the liability relates to goods, the person in charge of the goods is deemed the taxable person liable. The taxable person may apply within thirty days to challenge the order, and the Additional or Joint Commissioner may withdraw an erroneous order and proceed under the statute's regular assessment procedure.