Where [* * * *] refund of any tax becomes due to a registered dealer, he shall, subject to rules, if any, be entitled to receive, in addition to the refund, simple interest at the prescribed rate on the amount of refund for the period commencing on the date next following the [last date of the period to which the refund relates and ending on the date of the order sanctioning the refund] or for a period of twenty-four months, whichever is less. The interest shall be calculated on the amount of refund due to the registered dealer in respect of the said period after deducting therefrom the amount of penalty, sum forfeited and interest, if any, charged in respect of the said period and also the amount refund, if any [adjusted towards any recovery under this Act, any earlier law] or as the case may be, under the Central Sales Tax Act, 1956 (74 of 1956). If, as a result of any order passed under this Act, the amount of such refund is enhanced or reduced, as the case may be, such interest shall be enhanced or reduced accordingly. If the interest is reduced, then the amount granted in excess shall be recovered as if it is an amount payable under this Act :
[Provided that, interest under this section shall not be granted towards any [* * * *] refund granted under section 51.]
Explanation.- For the purposes of this section, where the refund of tax, whether in full or in part, includes any amount of refund on any payment of tax made after the date prescribed for making the last payment in respect of the said period, then the interest, in so far as it relates to the refund arising from such payment, shall be calculated from the date of such payment on the date of such order.