4.—1. The amount of the rebate is the difference between the total amount of credit repayments that would be due after the settlement date if no early settlement had taken place and the amount indicated by the following formula: Regulations 4 to 6 differ from the corresponding provisions of the 1983 Regulations. Rule 4 contains an actuarial formula: which is used in the calculation of the amount of the rebate instead of the formulas provided for in the 1983 Regulations for various cases. The calendar includes examples that illustrate the application of the new formula. Rule 5 specifies the billing date to be used to calculate the discount. It differs from the corresponding provision of the 1983 Regulations in that the relevant date under that provision was generally determined on the basis of the date of the next instalment due under the Agreement […].