The assessee filed original return and revised return of income prior to the issuance of any notice under section 148. The assessee had claimed deduction of interest paid to financial institutions and banks during the previous years relevant to the assessment years 1999-2000 and 2000-01. No intimation under section 143(1)(a) was sent by the Assessing Officer. Even if the acknowledgment of return was treated to be an intimation under section 143(1)(a), yet it was not an assessment order. Since there was no original assessment proceeding and assessment order, the question of reassessment did not arise. The order passed by the Assessing Officer to  not a reassessment order but an assessment order pursuant to the original and revised returns filed by the assessee. The assessee claimed interest as deductible expenditure under section 43B and its admissibility was not disputed by the Assessing Officer. The proceedings before the Assessing Officer not being reassessment proceedings, the assessee had lawfully claimed interest as a deducible expenditure which the Assessing Officer was bound to have allowed. The charge of tax was on the income and not on gross receipts. It was the profits and gains of business or profession which had to be computed after deducting the losses and expenditures incurred for business. Interest is an allowable expenditure. Order of Tribunal is set aside.  CIT v. Sun Engineering Works P Ltd. [1992] 198 ITR 297 (SC), (1992) 4 SCC 363 distinguished.(AY. 1999-2000, 2000-01)