03 July 2012
1. As per Section 139(1), income tax return should be filed on or before the due date of filing the return (31st July/30th September, as the case may be).
2. Section 139(4) provides that the assessee may file a belated return if he has not filed a return on or before the due date. Such return can be filed upto one year from the end of the Assessment Year or completion of assessment, whichever is earlier.
When this period of one year is over and the assessee has not filed the return, the return becomes time barred (as the time to file the same has expired).
Now the assessee cannot file the return for that particular Assessment Year.
For instance, return for AY 10-11 and previous year is now time barred.