Certain employment based preference categories require a Labor Certification. A US employer who is sponsoring an immigrant is required to obtain a verification from the Department of Labor that there are insufficient available, qualified and willing workers to fill the position, and that the employment will not have an adverse effect on the wages and working conditions of similarly situated U.S. workers. Labor Certification is a process by which the employer tests the market to establish the above criteria.

As of March 2005, PERM (Program Electronic Review Management), a new Labor certification procedure, was established for faster processing of the labor certifications.