(1) The compensation payable to the commercial employee pursuant to section 74 (2) is to be paid at the end of each month.
(2) Insofar as the contractual remuneration for the employee consists of commissions or other variable payments, the average thereof received over the last three years is to be used to calculate the compensation due. Where, at the time of termination of the employment relationship, the applicable contract provision regarding remuneration has been in existence for less than three years, the calculation is to be based on the average during the period for which such provision has been in force.
(3) Insofar as payments are intended to compensate for specific expenses arising in connection with the employment, they will not be included in the calculation.