It is a general principal in the entire income tax act that when the Income is exempt then the expense is not allowed. So while calculating dividend which are exempt in hands of Assessee i e. on which CDT is being paid by Co. , No Expense shall be allowed.
In respect of 115BBDA it is clearly mentioned under 115BBDA(2) that No expenses or set off etc shall be allowed for such dividend given u/s 115BBDA(1).