29 C.F.R. § 1620.32

(a) Employers having employees subject to the Act are required to keep records in accordance with U.S. Department of Labor regulations found at 29 CFR part 516 (Records To Be Kept by Employers Under the FLSA). The regulations of that part are adopted herein by reference.

(b) Every employer subject to the equal pay provisions of the Act shall maintain and preserve all records required by the applicable sections of 29 CFR part 516 and in addition, shall preserve any records which he makes in the regular course of his business operation which relate to the payment of wages, wage rates, job evaluations, job descriptions, merit systems, seniority systems, collective bargaining agreements, description of practices or other matters which describe or explain the basis for payment of any wage differential to employees of the opposite sex in the same establishment, and which may be pertinent to a determination whether such differential is based on a factor other than sex.

(c) Each employer shall preserve for at least two years the records he makes of the kind described in § 1620.32(b) which explain the basis for payment of any wage differential to employees of the opposite sex in the same establishment.