(a) The average weekly wage used to determine temporary income benefits for all part-time employees shall be calculated according to the basic calculation described in §128.3(d), (e), or (g) of this title (relating to Average Weekly Wage Calculation for Full-Time Employees, and for Temporary Income Benefits for All Employees).
(b) For purposes of calculating average weekly wage for all other income and death benefits, part-time employees are considered in two different categories: those who worked part-time as a regular course of conduct, and those who did not. A "regular course of conduct" for part-time work shall be determined by reviewing the work history of the employee for the 12-month period preceding the injury. If the employee only worked part-time during that period, the employee is presumed to have worked part-time as a regular course of conduct unless such presumption is rebutted by credible evidence.
(c) For an employee who worked part-time as a regular course of conduct, §128.3(d), (e), or (g) of this title (relating to Average Weekly Calculation for Full-Time Employees, and for Temporary Income Benefits for All Employees) shall be used to calculate average weekly wage to determine impairment income, supplemental income, lifetime income, and death benefits.
(d) The average weekly wage for a part-time employee who did not work part-time as a regular course of conduct shall be calculated by using one of the two methods in subsection (e) or (f) of this section, depending upon the length of time the person was employed.
(e) For an employee who worked for the employer for 13 or more consecutive weeks before the date of injury, the person calculating benefits shall derive the average weekly part-time wage, and then adjust upward to a full-time average weekly wage, by this method:
  (1) add together the wages for the 13 weeks immediately preceding the date of injury and divide the total by 13;
  (2) then add together the number of hours worked by the employee during the same 13 weeks, and divide the total hours by 13 to calculate the average weekly number of hours worked. The adjustment factor is the ratio of the number of full-time hours generally worked by similar employees in the same employment, over the average weekly number of hours worked by the injured employee. (Example: if the usual full-time hours for the employment is 40, and the average number of hours worked by the injured part-time employee is 30, then the adjustment factor derived is 40/30, or 1.334.) For purposes of the adjustment factor, it shall be presumed that a full-time work week is 40 hours, unless and until evidence establishes that use of a different number of hours would be more just;
  (3) finally, multiply the result of paragraph (1) of this subsection by the adjustment factor derived in paragraph (2) of this subsection; the product is the average weekly wage for this injured employee.
(f) For an employee who worked for the employer less than 13 weeks or whose wage at the time of injury cannot be fixed or determined, the average weekly wage will be calculated by using the method described in §128.3(e) of this title (relating to Average Weekly Wage Calculation for Full-Time Employees, and for Temporary Income Benefits for All Employees), based upon identification of a similar employee performing similar employment full-time.

Source Note: The provisions of this §128.4 adopted to be effective January 11, 1991, 16 TexReg 118.