Question . Is a labor certification application and I-140 valid for only one employer? Does a change of employer make the above approvals void?
The labor certification and the I-140 is only applicable for a specific employer and offer of employment in the United States. Changing the employer requires that the person start the process over from the beginning with the possibility that the priority date can be maintained, in some instances.
 
However, it may be possible for one to change jobs without having to initiate a new "green card" case under the American Competitiveness in the 21st Century Act (AC21). Section 106(c) of AC21 provides that the approved I-140 continues to remain valid for purposes of adjustment of status when the person changes employers, if the following two conditions are met:
 
a) The I-485 or the application to adjust status, on the basis of the employment-based (EB) immigrant petition, has been filed and remains unadjudicated for over 180 days or longer; and
b) The new job offer is in the same or similar occupational classification as the job for which the certification or approval was initially made.