Great question! "Hours worked" should include all employee work hours (include non-employees that your company supervises) during a 12-month period. You should not include hours for which an employee did not work such as vacation, sick leave, holidays, etc. (even if such hours were paid). If actual hours worked are not available for employees paid on commission, by salary, or by the mile, etc., hours worked may be estimated on the basis of scheduled hours or 8 hours per workday.