Held that  under section 151 of the Income-tax Act, 1961 a notice under section 148 of the Act cannot be issued after the expiry of a period of four years from the end of the relevant assessment year, unless the Principal Chief Commissioner or Chief Commissioner or Principal Commissioner or Commissioner was satisfied, on the reasons recorded by the Assessing Officer, that it was a fit case for the issue of such a notice. Since the assessment year under consideration was 2015-16 and the notice dated March 29, 2021 was admittedly beyond the four year period for which the approval ought to have been granted by any one of the four authorities and not by the Joint Commissioner. The Assessing Officer fell in error in holding that the case at hand fell within the four years period, from the end of the assessment year under consideration. The notice is  invalid.(AY.2015-16)