23A. ADDITIONAL PROVISIONAL TAX PAYMENTS
(1) Any provisional taxpayer may for the purpose of avoiding or reducing his liability for any interest which may become payable by him in respect of any year of assessment under section 89quat, elect to make an additional payment of provisional tax in respect of such year.
(2) If any additional payment of provisional tax contemplated in subparagraph (1) is paid after the end of the period ending on the effective date in relation to the said year as determined under section 89quat(1), such payment shall be deemed for the purposes of section 89bis(2) to be an amount of provisional tax which was payable within the said period.