Section II B of the State Act during the relevant period provided inter alia as under: "11B. Interest on failure to pay tax, fee or penalty (a) If the amount of any tax payable under sub sections (2) and (2A) of section 7 is not paid within the period allowed, or (b) If the amount specified in any notice of demand, whether for tax, fee, or penalty, is not paid within the period specified in such notice, or in the absence of such specification, within 30 days from the date of service of such notice, the dealer shall be liable to pay simple interest on such amount at one per cent per month from the day commencing after the end of the said period for a period of three months and at one and a half per cent per month thereafter during the time he continues to make default in the payments; 573 Provided that, where, as a result of any order under this Act, the amount, on which interest was pay able under this section, has been reduced, the interest shall be reduced accordingly and the excess interest paid, if any, shall be refunded: Provided further that no interest shall be payable under this section on such amount and for such period in respect of which interest is paid under the provisions of sections 11 and 14.