Tax exemption under Section 10(46) recognizes specified non-commercial income of Tamil Nadu Water Board subject to filing and activity conditions. Notification under Section 10(46) designates the Tamil Nadu Water Supply and Drainage Board as entitled to exemption for specified incomes: centage prescribed by the State, water charges collected from local bodies for bulk supply at State-fixed tariffs, and interest, rent and deposits from local bodies. The exemption is conditional on the Board not engaging in commercial activity, the continuity of its activities and income nature during the financial year, and filing the return of income as required by clause (g) of sub-section (4C) of section 139. The notification covers financial years 2013-14 to 2017-18.