Where the assessment of a charitable trust, registered under section 12AA, was completed under section 143(3) of the Income-tax Act, 1961, the Assessing Officer issued a notice under section 148 after four years. The reason for reopening was that income from hall charges was allegedly commercial in nature and had escaped assessment. The High Court quashed the notice, holding that since the reasons for reopening explicitly stated that the information regarding this income was obtained from the assessee’s return of income, there was no failure on the part of the assessee to disclose fully and truly all material facts. Consequently, the mandatory condition under the proviso to section 147 of the Income-tax Act, 1961 for reopening an assessment after four years was not fulfilled. (AY. 2007-08)