Interest added when estimated payment on dividends, interest income or capital gains is less than minimum required.

(b) If any part of the interest referred to in subsection (a) of this section with respect to tax for any taxable year is not paid to the commissioner on or before the due date for filing the final return for such taxable year prescribed in said section 12-508 , such unpaid interest shall be added to the tax imposed under section 12-506 for such taxable year. (c) If any installment payment, as required in section 12-517a , is less than the minimum amount required under this section for such income year, a penalty shall be imposed with respect to such payment in the amount of ten per cent of the part of such installment which is less than such minimum amount, or fifty dollars, whichever amount is greater. (d) The commissioner shall waive any penalty applicable with respect to gains from the sale or exchange of capital assets earned, received in fact or constructively, accrued or credited to a taxpayer, in the calendar year commencing January 1, 1989, whose adjusted gross income, reduced by the amount of any such gains, is less than fifty-four thousand dollars.