With respect to each employee compensated for overtime hours at a “basic” rate which is substantially equivalent to the employee's average hourly earnings, as authorized in accordance with section 7(g)(3) of the Act and part 548 of this chapter, employers shall maintain and preserve records containing all the information and data required by § 516.2 except paragraph (a)(6) thereof and, in addition, the following:
(a)
(1) The hourly rates, piece rates, or commission rates applicable to each type of work performed by the employee,
(2) The computation establishing the basic rate at which the employee is compensated for overtime hours (if the employee is part of a workforce or employed in or by an establishment all of whose workers have agreed to accept this method of compensation, a single entry of this computation will suffice),
(3) The amount and nature of each payment which, pursuant to section 7(e) of the Act, is excluded from the “regular rate.”
(b)
(1) Identity of representative period for computing the basic rate,
(2) the period during which the established basic rate is to be used for computing overtime compensation,
(3) information which establishes that there is no significant difference between the pertinent terms, conditions and circumstances of employment in the period selected for the computation of the basic rate and those in the period for which the basic rate is used for computing overtime compensation, which could affect the representative character of the period from which the basic rate is derived.
(c) A copy of the written agreement or, if there is no such agreement, a memorandum summarizing the terms of and showing the date and period covered by the oral agreement or understanding to use this method of computation. If the employee is one of a group, all of whom have agreed to use this method of computation, a single memorandum will suffice.