Income-tax exemption under clause 10(46) granted to Chandigarh construction workers welfare board; specified cess, contributions and interest exempt. Exemption under clause (46) of section 10 is accorded to the Chandigarh Building and Other Construction Workers Welfare Board for specified receipts: cess proceeds, beneficiary contributions and registration fees, and interest earned thereon, subject to conditions that the Board shall not engage in commercial activity, its activities and the nature of specified income remain unchanged, and it files returns as required by clause (g) of sub-section (4C) of section 139; the notification is given retrospective effect for the stated assessment years.