Assessment under Income Tax Act 1961 means a written order of computation of total income by the assessing officer. The assessment of total income is done under different circumstances. One is when a person files return of income and the a processing by computer is done to assess the total income , tax payable or refundable. Then there is assessment after scrutiny under section 143(3). Similarly when search and seizure is conducted under section 132 of the Income Tax Act, A.O passess order fo assessment u/s 153A or 153C as teh case may be . Assessment also include reassessment.