For the purpose of this Article, the annual salary of an employee whose salary or wage is appropriated, fixed, or arranged in the annual appropriation ordinance upon other than an annual basis shall be determined as follows:
"Monthly salary" means the amount of compensation or salary appropriated and payable for a normal and regular month's work in the employee's position in the service. "Weekly salary" means the amount of compensation or salary appropriated and payable for a normal and regular week's work in the employee's position in the service. If the work is on a regularly scheduled part time basis, then "monthly salary" and "weekly salary" refer, respectively, to the part time monthly or weekly salary.
If the appropriation for the position is for a shorter period than 12 months a year, or 52 weeks a year if on a weekly basis, or the employee is in a class, grade, or category in which the employee normally works for fewer than 12 months or 52 weeks a year, then the basis shall be adjusted downward to the extent that the appropriated or customary work period is less than the normal 12 months or 52 weeks of service in a year.
Compensation for overtime, at regular or overtime rates, that is paid in addition to the appropriated regular and normal monthly or weekly salary shall not be considered.
The norm is based on a 12-month per year, 5-day work week of 8 hours per day and 40 hours per week, with consideration given only to time compensated for at the straight time rate of compensation or wage. The norm shall be increased (subject to a maximum of 300 days or 2400 hours per year) or decreased for an employee to the extent that the normal and established work period, at the straight time compensation or wage for the position held in the class, grade, or category in which the employee is assigned, is for a greater or lesser number of months, weeks, days, or hours than the period on which the established norm is based.
"Daily wage" and "hourly wage" mean, respectively, the normal, regular, or basic straight time rate of compensation or wage appropriated and payable for a normal and regular day's work, or hour's work, in the employee's position in the service.
Any time worked in excess of the norm (or the increased or decreased norm, whichever is applicable) that is compensated for at overtime, premium, or other than regular or basic straight time rates shall not be considered as time worked, and the compensation for that work shall not be considered as salary or wage. Such time and compensation shall in every case and for all purposes be considered overtime and shall be excluded for all purposes under this Article. However, the straight time portion of compensation or wage, for time worked on holidays that fall within an employee's established norm, shall be included for all purposes under this Article.
40 ILCS 5/8-233