To file itr or not ?

I have two cases:-

Case 1

I am working  with Tata Consultancy Services working in USA since Feb 2011. As a resulted I earned nothing in india from salary or from other sources for FY 2011-12. My interest income from Bank Savings is around Rs 20,000. Do i have to file income tax ?

Case 2:

My wife is working in india but is on Leave without pay since Feb 2011 and she is with me in USA and as a result of LWP she has also earned nothing from income or other sources. Her interest income is around Rs 15,000. Does she have to file Income tax for Fy 2011-12. If yes, can she file by March 2013 as last date as no tax or refund is due ??