02 March 2012
234 A is applicable only when the return is filed after the due date. 234 B is chargeable for default in payment of advance tax for the period from 1st April next following the FY to the date of determination of Income u/s 143(1) or the date of regular assessmen on assessed tax or on the amount by which advance tax paid falls short of the assessed tax. Even if you have received refund you can calculate the interest as above and check the correctness of the Assessment order.