(4)For the purpose of enabling the Board to assess the amount of the duty of excise levied under this section-(a)the Board shall, by notification in the Official Gazette, fix a period in respect of which assessments shall be made ; and(b)without prejudice to the provisions of section 20, every owner and every manufacturer shall furnish to the Board a return not later than [thirty days] [Substitution for the words 'fifteen days' by Act 4 of 2010 ] after the expiry of the period to which the return relates, stating,-(i)in the case of an owner, the total quantity of rubber produced on the estate in each such period :Provided that in respect of an estate situated only partly in India, the owner shall in the said return show separately the quantity of rubber produced within and outside India ;(ii)in the case of a manufacturer, the total quantity of [rubber acquired] [Substitution for the words 'rubber used' by Act 4 of 2010 ] by him in such period out of the rubber produced in India
