Paragraph 3
The licensee shall pay to the system operator an amount representing 8 per cent above the base interest rate of any payment not made to the system operator on the date specified pursuant to paragraph 2 calculated for each day after the date on which payment should have been made which interest payment shall be made by the licensee as soon as possible after, and in any event within 28 days, of the date of the invoice from the system operator for such payment.