Nonexempt work in the definition of "outside salesperson" is limited to "20 percent of the hours worked in the workweek by nonexempt employees of the employer." The 20 percent is computed on the basis of the hours worked by nonexempt employees of the employer who perform the kind of nonexempt work performed by the outside salesperson. If there are no employees of the employer performing this nonexempt work, the base to be taken is 40 hours a week, and the amount of nonexempt work allowed will be 8 hours a week.
Iowa Admin. Code r. 875-218.507
29 CFR 541.507.