¹[7D. Interest payable by assessee in case of underestimate, etc.--Where, on making the regular assessment, the ²[Assessing Officer] finds that any company has under section 7A underestimated the advance surtax payable by it and thereby reduced the amount payable in either of the first two instalments, he may direct that the company shall pay simple interest at ³[fifteen per cent.] per annum for the period during which the payment was deficient, on the difference between the amount paid in each such instalment and the amount which should have been paid, having regard to the aggregate advance surtax actually paid during the year.
     Explanation.--For the purposes of this section, any instalment due before the expiry of six months from the commencement of the previous year in respect of which it is to be paid shall be deemed to have become due fifteen days after the expiry of the said six months.]