The Assessing Officer made an assessment under section 143(3). In doing so, the Assessing Officer clearly took into consideration the disclosures made by the assessee in its return of income. On the said basis, the Assessing Officer allowed the claim of the assessee and set off the loss of PPGM for the financial year 1998-99 against the book profits of the assessee for that financial year for the purposes of determining the assessee’s MAT liability under section 115JA. After expiry of four years from end of relevant assessment year, the Assessing Officer initiated reassessment proceedings taking a view that assessee’s claim for set off of loss PPGM against its book profits was wrongly allowed. On writ the Court held that  Assessing Officer considered all relevant materials disclosed by assessee and thereafter allowed assessee’s claim for set off of loss of company amalgamated with it against its book profits while determining MAT liability, in absence of any failure on assessee’s part to disclose truly and fully all material facts necessary for assessment, Assessing Officer could not initiate reassessment proceedings after expiry of four years from end of relevant year merely on basis of change of opinion that aforesaid loss was wrongly set off . ( AY.1999 -2000 )