Void transfers during tax proceedings prevent dispositions that defeat tax claims unless made for adequate consideration or with officer permission. Section 281 voids dispositions of specified assets made during pendency of tax proceedings, or after completion but before service of notice under rule 2 of the Second Schedule, insofar as they affect recovery of tax or other sums payable; exceptions apply where transfers are for adequate consideration without notice of the proceeding or tax claim, or where they are made with prior permission of the Assessing Officer, and the provision operates subject to monetary thresholds and a restricted definition of assets excluding stock in trade.