Employers with 1 or more employees must comply with;

Fair Labor Standards Act (FLSA)

Employee Polygraph Protection Act

Immigration Reform & Control Act (IRCA)

Equal Pay Act

Uniformed Services Employment & Re-employment Rights Act of 1994

National Labor Relations Act (NLRA)

Consumer Credit Protection Act

Labor Management Relations Act

Uniform Guidelines for Employment Selection Procedures

Employment Retirement Income Security Act (ERISA)

Federal Income Tax Withholding, and  Federal Insurance Contribution Act (FICA)

Employers with 11 or more employees also need to comply with;

Occupational Safety & Health Act (OSHA Illness/Injury Recording and Reporting Requirements)

Employers with 15 or more employees must also follow;

Pregnancy Discrimination Act

Americans with Disabilities Act

Civil Rights Act of 1964

Employers with 20 or more employees also need to comply with;

Age Discrimination in Employment Act

Consolidated Omnibus Budget Reconciliation Act (COBRA)

*Employers with 50 employees or more also need to comply; (*Executive Order 11246, requires federal contractors with 50 or more employees and $50,000 in government contracts must also file EE0-1 report each year).

Family Medical Leave Act (FMLA)

Finally, employers with 100 or more employees must comply with the;

Worker Adjustment Retraining Notification Act (WARN)

And must complete and report the EEO-1 form to the EEOC

Source:  Society for Human Resources Management Website