Section 4(1)(a) in The Black Money (Undisclosed Foreign Income And Assets) And Imposition Of Tax Act, 2015
(a)the income from a source located outside India, which has not been disclosed in the return of income furnished within the time specified in Explanation 2 to sub-section (1) or under sub-section (4) or sub-section (5) of section 139 of the Income-tax Act;