Assessee spent certain amount towards product development expenditure  which was claimed as revenue expenditure . After four years, Assessing Officer reopened assessment on ground that assessee had shown only a portion of product development expenditure under profit and loss account and, therefore, assessee was entitled to claim income-tax benefit only to that extent and, hence, he disallowed remaining amount. Assessee contended that the amount debited in profit and loss account was relating to previous assessment year, which was 1/3rd of product development expenses for which it was amortizing in relevant year. CIT (A) quashed the reassessment order which was affirmed by the Appellate Tribunal . On appeal by the revenue the Court held that there was no justifiable reason to reopen assessment under  after four years , further since product development expenditure incurred by assessee was revenue in nature, there was no error in deduction claimed by assessee though said expenditure was to be amortized over period of three years as per accounting practice adopted by company .  (AY. 2007-08)