(1)No order of assessment shall be made under section 143 or section 144 at any time after the expiry of twenty-one months from the end of the assessment year in which the income was first assessable:Provided that in respect of an order of assessment relating to the assessment year commencing on the 1st day of April, 2018, the provisions of this sub-section shall have effect, as if for the words "twenty-one months", the words "eighteen months" had been substituted:[Provided further that in respect of an order of assessment relating to the assessment year commencing on the—(i)1st day of April, 2019, the provisions of this sub-section shall have effect, as if for the words "twenty-one months", the words "twelve months" had been substituted;(ii)1st day of April, 2020, the provisions of this sub-section shall have effect, as if for the words "twenty-one months", the words "eighteen months" had been substituted:][Provided also that in respect of an order of assessment relating to the assessment year commencing on or after the 1st day of April, 2021, the provisions of this sub-section shall have effect, as if for the words "twenty-one months", the words "nine months" had been substituted.][(1A) Notwithstanding anything contained in sub-section (1), where a return under sub-section (8A) of section 139 is furnished, an order of assessment under section 143 or section 144 may be made at any time before the expiry of nine months from the end of the financial year in which such return was furnished.]
