Tax exemption for undisclosed income invested in National Defence Gold Bonds shields such income from inclusion in taxable income. Where undisclosed income has been used to acquire gold and that gold is tendered as subscription for National Defence Gold Bonds prior to detection or seizure, the income represented by that gold shall not be included in taxable income, and the corresponding asset value shall not be taken into account in computing net wealth for specified assessments and reassessments. Subscriber names and bond particulars are confidential and public servants are prohibited from disclosure except to officers engaged in specified tax, audit or administrative functions; 'gold' and 'public servant' are given inclusive definitions.