18 August 2011
It has not been mentioned whether you wish to return in City A. . In case you do not have any such plan to return, it is always advisable to get changed your address in the PAN data. Also intimate the jurisdictional AO by intimating him about your change in the place of employment, and if possible intimate about the jurisdictional ITO of City Z in the same letter. .
As e filing is possible nowadays, you can file your return from city Z only. . The period of 5-6 is also a long period so it is better to change the address in PAN Data.