The assessee’s original assessment was completed under section 143(3). More than four years after the end of the relevant assessment year, the Assessing Officer issued a notice under section 148 to reopen the assessment. The reason provided was that the deduction under section 80HHC should have been calculated after setting off brought-forward losses against the adjusted business profit. The High Court quashed the reassessment proceedings. It held that as the reopening was initiated after four years from a scrutiny assessment, the proviso to section 147 required the Revenue to establish a failure on the part of the assessee to fully and truly disclose all material facts. The reasons recorded did not indicate any such failure but were based on a re-examination of the same material already on record. This constituted a mere change of opinion, and an error discovered upon such reconsideration does not grant the Assessing Officer the power to reopen an assessment. (AY. 2003-04)