To get an immigrant visa based on employment, a U.S. business must sponsor you. The U.S. business must first obtain a labor certification, stating that there is an unavailability of U.S. workers for the employment position. The alien must then file an INS Form I-140 along with the labor certification, and the INS has to approve the petition. Proof of education and experience must also accompany the petition, and the sponsoring U.S. company has to submit proof that it can pay the alien a salary.
Although someone who comes into the United States on an employment-based visa does not have to keep the offered position permanently, if the immigrant quits soon thereafter, it could raise flags with the INS indicating the job offer wasn’t genuine and was only made to get the immigrant a visa.
* Employment Based Visa Preferences