Federal law prohibits employers from hiring or continuing to employ an unauthorized alien. The work status of new employees can be verified using the Electronic Verification Program (E-Verify), administered by the U.S. Department of Homeland Security and the Social Security Administration.
Conducting an E-Verify search involves matching a social security number and other information reported on Form I-9, Employment Eligibility Verification, to government records.
- Can only be used after an individual accepts an offer of employment and completes Form I-9.
- Must be used within three business days of the new hire’s actual start date.
- Cannot be used to verify the eligibility status of existing employees.
- Must be used to verify the work status of all new hires if an employer elects to use it, regardless of national origin or citizenship.
- Cannot be used selectively.
As with all current employee-verification programs, E-Verify is not always accurate. If a new employee is legally documented to work in the U.S. but the employer receives a final notice of nonconfirmation of work eligibility for the employee through E-Verify, there is recourse for the employee. Visit the employees section of the U.S. Citizenship and Immigration Services website.
For information about the employee’s identity documents presented for Form I-9, Employment Eligibility Verification, visit www.uscis.gov. Useful information is also available on the Employment Verification Law page at the Colorado Department of Labor and Employment.
It is unlawful for an employer to:
- Hire, recruit, or refer for a fee, for employment in the United States, an alien, knowing the alien is an unauthorized alien;
- Hire, recruit, or refer for a fee, for employment in the United States, an individual without verifying the employment eligibility status of the individual through completion of the Form I-9, or its successor form;
- Continue to employ an alien in the United States, knowing that the alien is or has become an unauthorized alien; or
- While using the E-Verify program, refuse to hire, discharge, promote, or demote a person, harass a person during the course of employment, or discriminate against a person in matters of compensation, on the basis of the person’s disability, race, creed, color, sex, sexual orientation, religion, age, national origin, or ancestry. 
For more specific information regarding the E-Verify program and its requirements and use, employers should consult 8 U.S.C. Sec. 1324a (PDF).
 24-34-402, C.R.S.