According to the U.S. Equal Employment Opportunity Commission, there are a few things you need to do in terms of employee data. Employers must keep payroll records for three years. Employers must also keep employee records for two years in order to explain the basis for paying different wages for employees of opposite sexes in the same establishment. These records include wage rates, job evaluations, merit systems, etc.
Reference: “Recordkeeping Requirements.” U.S. Equal Employment Opportunity Commission, n.d. https://www.eeoc.gov/employers/recordkeeping-requirements