(2)The amount of duty paid at each proceeding stage of sale shall be adjusted against the amount of duty payable at each subsequent stage of sale in the manner prescribed:Provided that if the sale of energy at any subsequent points is not leviable to duty under sub-section (2) of Section 3, the liability, in respect of any subsequent period, of the proceeding seller shall stand reduced, in the manner prescribed, to the extent of the duty paid by him in respect of such subsequent sale of energy as is not leviable to duty under sub-section (2) of Section 3."
