Summary assessment powers protect revenue by allowing expedited tax assessment where delay may prejudice collection. Summary assessment permits a proper officer, with prior approval of an Additional or Joint Commissioner, to make an expedited tax assessment when evidence of tax liability emerges and delay would harm revenue; if the taxable person is unascertainable for supply of goods, the person in charge of the goods is deemed the taxable person; the senior officer may withdraw an erroneous summary order and direct reassessment under the ordinary procedure.