3. The duty payable by electric power or natural gas distributors and by the electric power carrier is payable in equal instalments on the first day of each month.
The amount of the last monthly instalment continues to apply until the last day of the month during which the expenditure estimates are adjusted as provided in the second paragraph of section 1 and the third paragraph of section 2. Any overpayment of or amount owing on the duty payable to the Régie for the fiscal year is to be equally apportioned over the remaining monthly instalments.
The annual duty payable by petroleum products, fuel or steam distributors is payable in one instalment on the first day of the month following the month in which the expenditure estimates are adjusted as provided in the second paragraph of section 1.