“ 10. Sub-section (2B) of section 11A provides that the assessee in default may, before the notice issued under subsection (1) is served on him, make payment of the unpaid duty on the basis of his own ascertainment or as ascertained by a Central Excise Officer and inform the Central Excise Officer in writing about the payment made by him and in that event he would not be given the demand notice under sub-section (1). But Explanation 2 to the sub-section makes it expressly clear that such payment would not be exempt from interest chargeable under section 11AB, that is, for the period from the first date of the month succeeding the month in which the duty ought to have been paid till the date of payment of the duty. What is stated in Explanation 2 to sub-section (2B) is reiterated in section 11AB that states where any duty of excise has not been levied or paid or has been short levied or short paid or erroneously refunded, the person who has paid the duty under sub-section (2B) of section 11A, shall, in addition to the duty, be liable to pay interest......It is thus to be seen that unlike penalty that is attracted to the category of cases in which the non-payment or short payment etc. of duty is "by reason of fraud, collusion or any wilful mis-statement or suppression of facts, or contravention of any of the provisions of the Act or of