Tribunal held that as far as section 292BB was concerned, the objection to service of notice stood waived if the assessee had participated in the assessment proceedings. But in the instant case, according to the proviso to section 143(2) of the Act, no notice could have been served on the assessee after the expiry of the six-month period from the end of the financial year in which return was filed. Accordingly, the notice dated September 1, 2011 issued by the Commissioner, Circle-37(1) was without jurisdiction and invalid and the notice dated August 30, 2012 issued by the ITO, Ward-38(2), New Delhi issued by the correct jurisdictional Officer, was beyond the period of limitation and therefore, also invalid. The assessment order was void ab initio and liable to be quashed.( AY.2010-11)