23. (1) In computing the income under the head “Interest on securities”, the following allowances and deduction shall be made, namely:- (a) any sum deducted from interest by way of commission or charges by a bank realising the interest on behalf of the assessee; (b) any interest payable on money borrowed for the purpose of investment in the securities by the assessee ¹[: Provided that no allowance or deduction on account of any interest or commission paid under clause (a) or (b), as the case may be, in respect of, or allocable to the securities of Government which have been issued with the condition that interest thereon shall not be liable to tax, shall be made in computing the income under section 22.] ²[* * *] (2) Notwithstanding anything contained in sub-section (1), no deduction shall be allowed under this section in respect of any interest payable outside Bangladesh on which tax has not been paid or deducted in accordance with the provisions of Chapter VII.