(1) Where a dealer fails to make payment of any tax due after provisional or other assessments by the date specified in the notice issued under section 45 or section 46 or section 48 for payment thereof, he shall, subject to the provisions of sub-section (2), pay a simple interest at the rate of twelve per centum per annum for the period of default, calculated from the day next following the date specified in such notice up to the day of full payment of such tax or up to the day preceding the day of commencement of proceedings under section 55, whichever is earlier upon so much of the amount of tax payable by him according to such notice as remains unpaid.

(2) Where as a result of an order under section 84, section 85, section 86, section 87 or section 88 the amount of tax payable is modified, the interest payable under sub-section (1) shall be determined or re-determined on the basis of such modified amount and the excess interest paid, if any, shall be refunded.