Query regarding levy of interest u/s 234a,b,c

Our client has filed his return of income for A.Y 2014-15 on 26/03/2015. Subsequently I.T department has sent a communication treating the return as defective U/s 139(9) on 20/08/2015. The total income submitted in the original return filed was around Rs.9,00,000/- and after rectifying the defects the total income is Rs.11,00,000/-. Now there arises a tax liability of more than Rs.80000/- due to the defects corrected. This tax liability is after the advance tax and the original self assessment tax paid. Out of the tax liability of Rs.80,000, the interest component is around Rs.40,000. Now my query is – a) Whether we need to re-calculate the interest from the date of filing of the original return to the date of filing the defective return i.e.(period between the original return filing date and date of filing the defective return) or b) Should we calculate the interest U/s 234A,B,C according to their due dates.