17 August 2007
Sec.234A applies where income tax return not filed in due time & interest payable @ 1% p.m from the due date till return filing date .
Sec.234B relating to Non Payment of Advance tax which comes in picture after 31 st march till payment date . Here interest also @1% p.m willbe applicable. Calculation is different for Individual assesses and Corporate Assesses. U can refer any text book for this purpose.