Result of non filing of income tax return?

In my view.

It is possible to file income tax returns in response to notice received. At the time of filling up the return you have to mention the Section number under which you have received the notice, your return would be accepted.

In the interim you can file a letter to the ITO asking him for time to file the returns. This would be considered as a sufficient compliance to the notice received and you can file your returns within the time you have requested for.

You can wait for other views as well.

It is possible to file the Return for AY 2010-11, but u have to pay  Interest u/s234A. If ur client is liable for Advance tax, then u have to pay Interest u/s 234B and 234C along with 234A