(820 ILCS 310/10) (from Ch. 48, par. 172.45)
    Sec. 10. The basis for computing the compensation provided for in Sections 7 and 8 of the Act shall be as follows:
    (a) The compensation shall be computed on the basis of the annual earnings which the person with a disability received as salary, wages or earnings if in the employment of the same employer continuously during the year next preceding the day of last exposure.
    (b) Employment by the same employer shall be taken to mean employment by the same employer in the grade in which the employee was employed at the time of the last day of the last exposure, uninterrupted by absence from work due to illness or any other unavoidable cause.
    (c) If such person has not been engaged in the employment of the same employer for the full year immediately preceding the last day of the last exposure, the compensation shall be computed according to the annual earnings which persons of the same class in the same employment and same location, (or if that be impracticable, of neighboring employments of the same kind) have earned during such period.
    (d) As to employees in employments in which it is the custom to operate throughout the working days of the year, the annual earnings, if not otherwise determinable, shall be regarded as 300 times the average daily earnings in such computation.
    (e) As to employees in employments in which it is the custom to operate for a part of the whole number of working days in each year, such number, if the annual earnings are not otherwise determinable, shall be used instead of 300 as a basis for computing the annual earnings, provided the minimum number of days which shall be so used for the basis of the year's work shall be not less than 200.
    (f) In the case of injured employees who earn either no wage or less than the earnings of adult day laborers in the same line of employment in that locality, the yearly wage shall be reckoned according to the average annual earnings of adults of the same class in the same (or if that is impracticable, then of neighboring) employments.
    (g) Earnings, for the purpose of this section, shall be based on the earnings for the number of hours commonly regarded as a day's work for that employment, and shall include overtime earnings. The earnings shall not include any sum which the employer has been accustomed to pay the employee to cover any special expense entailed on him by the nature of his employment.
    (h) In computing the compensation to be paid to any employee, who, before the disablement for which he claims compensation, was a person with a disability and drawing compensation under the terms of this Act, the compensation for each subsequent disablement shall be apportioned according to the proportion of incapacity and disability caused by the respective disablements which he may have suffered.
    (i) To determine the amount of compensation for each installment period, the amount per annum shall be ascertained pursuant hereto, and such amount divided by the number of installment periods per annum.
(Source: P.A. 99-143, eff. 7-27-15.)