For the assessment year 2013-2014, the assessee, an educational trust, without holding a valid registration under section 12AA of the Income-tax Act, 1961, at the time of filing the return of income under section 139(1), claimed exemption under section 11. The assessment was completed under section 143(1). Subseuently, the assessee was granted registration under section 12A(a). The assessee filed an application under section 154 for rectification of the assessment order, which was rejected. The Commissioner (Appeals) and the Tribunal rejected the assessee’s appeals. The Tribunal held that the assessee could not claim exemption as a trust for the assessment year 2013-2014, since it was not registered under section 12AA, and should have filed a revised return to claim deductions as a regular assessee or as an association of persons. On appeal, the Court held that the benefit of registration would not ensure in favour of the assessee after registration for the assessment year prior to the registration as trust. But the assessee could not be denied all the legitimate deductions that would have been available, if the returns were filed either as a regular assessee or as an association of persons. The purpose of assessment was to recover just tax and not subject the assessee to unjust tax by holding that no return was filed either as a regular assessee or as an association of persons merely because revised return was not filed under section 139(4), within the specified time. The last date for filing the returns under section 139(4) would have expired on March 31, 2015 which was just few days before the return was processed on March 12, 2015 under section 143(1). If assessments are to be completed, deductions and applicable exemptions that are otherwise available to an assessee ought to have been extended by the Assessing Officer to an assessee before finalising the assessment. Since the assessee was not entitled to exemption as a trust under sections 11, 12 and 12A in the absence of registration under the Act as it stood section 12AA, the benefit of other deductions under the Act ought to have been given. The Assessing Officer was not expected to act mechanically to confirm the liability to fasten an unjust tax liability on the assessee. The matter was remitted to the Assessing Officer to pass a fresh order.  Goeitze (India) Ltd v. CIT (2006) 284 ITR 323 (SC), distinguished. (AY. 2013-14)