Summary assessment empowers immediate protective tax assessments with supervisory permission and a review-withdrawal mechanism. The provision permits a proper officer, with prior permission of the Additional Commissioner or Joint Commissioner, to make a summary assessment and issue an assessment order when evidence of tax liability suggests delay would prejudice revenue; if the taxable person is unascertainable for goods supplies, the person in charge of the goods is deemed liable. A taxable person may apply within thirty days to challenge the order, and the Additional Commissioner or Joint Commissioner may withdraw an erroneous summary order and require follow-up under the ordinary assessment procedures.