Employees in the classified service, and employees in the unclassified service whose employment is covered by collective negotiation agreements which provide for longevity payments, shall be entitled to longevity payments to the extent and in the manner provided in such agreements.
Other employees in the unclassified service shall be entitled to receive, in addition to their regular salary, longevity pay in the amount of 1 1/2% of base salary for each completed four years of service, to a maximum of 7 1/2% of base salary, such longevity payments to become due, or to be appropriately increased, on the first day of the month following the month in which the employee's anniversary date of employment occurred.