(5)Nothing contained in this section shall apply unless the option is exercised by the person in the prescribed manner on or before the due date specified under sub-section (1) of section 139 for furnishing the returns of income for any previous year relevant to the assessment year commencing on or after the 1st day of April, 2020 and such option once exercised shall apply to subsequent assessment years:Provided that in case of a person, where the option exercised by it under section 115BAB has been rendered invalid due to violation of conditions contained in sub-clause (ii) or sub-clause (iii) of clause (a), or clause (b) of sub-section (2) of said section, such person may exercise option under this section:Provided further that once the option has been exercised for any previous year, it cannot be subsequently withdrawn for the same or any other previous year.
