Section 6(4) in The Oilfields (Regulation And Development) Act, 1948
(4)[ The Central Government may, by notification in the Official Gazette, amend the Schedule so as to enhance or reduce the rate at which royalty shall be payable in respect of any mineral oil with effect from such date as may be specified in the notification and different rates may be notified in respect of same mineral oil mined, quarried, excavated or collected from the areas covered by different classes of mining leases:Provided that the Central Government shall not fix the rates of royalty in respect of any mineral oil so as to exceed twenty per cent. of the sale price of the mineral oil at the oilfields or the oil well-head, as the case may be.
