29 C.F.R. § 1620.10
Under the EPA, the term "wages" generally includes all payments made to [or on behalf of] an employee as remuneration for employment. The term includes all forms of compensation irrespective of the time of payment, whether paid periodically or deferred until a later date, and whether called wages, salary, profit sharing, expense account, monthly minimum, bonus, uniform cleaning allowance, hotel accommodations, use of company car, gasoline allowance, or some other name. Fringe benefits are deemed to be remuneration for employment. "Wages" as used in the EPA (the purpose of which is to assure men and women equal remuneration for equal work) will therefore include payments which may not be counted under section 3(m) of the FLSA toward the minimum wage (the purpose of which is to assure employees a minimum amount of remuneration unconditionally available in cash or in board, lodging or other facilities). Similarly, the provisions of section 7(e) of the FLSA under which some payments may be excluded in computing an employee's "regular rate" of pay for purposes of section 7 do not authorize the exclusion of any such remuneration from the "wages" of an employee in applying the EPA. Thus, vacation and holiday pay, and premium payments for work on Saturdays, Sundays, holidays, regular days of rest or other days or hours in excess or outside of the employee's regular days or hours of work are deemed remuneration for employment and therefore wage payments that must be considered in applying the EPA, even though not a part of the employee's "regular rate."
29 C.F.R. §1620.10