Dismissing the appeal the Court held that admittedly, no certificates were produced by the assessee and inadvertently the Assessing Officer had allowed the deduction for the two years. On receipt of information by way of the appellate order, the Assessing Officer realised the escapement of assessment in the assessment years 1987-88 and 1988-89.  Reassessment is valid it is not change of opinion. (AY. 1987-88, 1988-89 )