The assessee  filed its return of income under section 139(1) declaring total income at Rs. Nil after claiming depreciation on straight line method  It was stated so in notes to account in balance sheet filed along with return of income in respect of exemption under section 10A.  Assessment order was passed  under section 143(3), after scrutiny, was issued on 31-1-2001. Notice under section 148 was issued to assessee, proposing to reassess income of assessee. On writ allowing the petition the Court held that there was not even an assertion that there was failure on part of assessee to disclose fully and truly all material facts, which was a mandatory requirement to assume jurisdiction by Assessing Officer.  Assessing Officer proceeded on ground that assessee had applied straight line method instead of written down value method in respect of depreciation which was a clear change of opinion. Accordingly there being absolutely no failure on part of assessee to disclose facts, reopening of assessment was not justified. (AY. 1998-99) (1997-98)