With respect to each employee exempt from the overtime pay requirements of the Act pursuant to section 13(b)(11), the employer shall maintain and preserve payroll or other records, containing all the information and data required by § 516.2(a) except paragraphs (a) (6) and (9) and, in addition, information and data regarding the basis on which wages are paid (such as the dollar amount paid per trip; the dollar amount of earnings per week plus 3 percent commission on all cases delivered). Records shall also contain the following information:

(a) A copy of the Administrator's finding under part 551 of this chapter with respect to the plan under which such employees are compensated;

(b) A statement or description of any changes made in the trip rate or other delivery payment plan of compensation for such employees since its submission for such finding;

(c) Identification of each employee employed pursuant to such plan and the work assignments and duties; and

(d) A computation for each quarter-year of the average weekly hours of full-time employees employed under the plan during the most recent representative annual period as described in § 551.8(g) (1) and (2) of this chapter.