Section 3B(7)(b) in The Rajasthan Electricity (Duty) Rules, 1970
(b)collect and pay within 15 days of the close of the month to which the duty relates in the Government treasury in Form IX as appended to these rules and send the duplicate-copy of the Treasury Challan to the Commissioner or to any officer authorized by him in this behalf so as to reach him within a period of 30 days from the close of the month to which the duty relates.