Assessment year is the period of twelve months commencing on the 1st day of April every year. It is given in the act and the Assessment year does not depend upon different Assessee. It is invariable as the calendar year.
As Per Income Tax Act, 1961- Assessment Year is defined as:
Assessment year means the period of twelve months commencing on the 1st day of April every year.
Related Case:
S. 2(9), 80HH, 145 of the IT Act, 1961—Deduction—The period of 12 months commencing from the first day of April every year, which is assessment year as defined u/s 2(9) of the Act, would not depend upon one or the other assessee and whether or not he had a previous year relevant to a particular assessment year. It is invariable as the calendar year and the assessment year mentioned in S. 80HH must be construed in a similar manner—CIT vs. Fal Industries Ltd. [2010]
Reference:
As Per Section 2(9) Of the Income Tax Act, 1961-
(9) “assessment year” means the period of twelve months commencing on the 1st day of April every year ;
(9A) “Assistant Commissioner” means a person appointed to be an Assistant Commissioner of Income-tax or a Deputy Commissioner of Income-tax under sub-section (1) of section 117 ;
(9B) “Assistant Director” means a person appointed to be an Assistant Director of Income-tax under sub-section (1) of section 117.