Defective ITR sectio 139(9) of Income Tax

Income Tax is filed in wrong ITR form, then you will get defective notice in sec 139(9).

In 15 days defective notice has to be replied. 

If we don't reply defective notice then it means you have not filed itr.

Note in case you don't e verify your tax return then it is invalid return like you have not file income tax return.