Here is more clarification on this topic,
Under the AC 21, 485 waiters are allowed to take new employment 180 days after filing I-485 inasmuch as it is a same or similar occupation. One question which remained a puzzle was what would happen if the employer should revoke the underlying approved I-140 petition. In fact, there have been a number of reports by the immigration lawyers that the Service Centers denied I-485 when underlying I-140 had been revoked by the employer in several instances.
This question has yet to be answered by the yet-to-be-enaced AC 21 regulation, but AILA has reported a letter written by a responsible BCIS official in response to an attorney's inquiry that revocation of the approved I-140 petition by the employer should not affect the pending I-485 application "inasmuch as the revocation took effect after 180 days from the filing of I-485." He opined that the underlying approved I-140 petition and the approved labor certification application would remain valid despite such revocation if it happened after 180 days.
The opinion was expressed in the form of a letter and not even an official memorandum. Accordingly, strictly speaking, the letter does not carry any legally binding force. However, in view of the fact that the officer is in charge of the business division, it should carry some weight for the Service Center adjudicators. Question remains: (1) Would the Service Center reverse their prior denial if people file a motion to reopen or motion to reconsider based on this letter? (2) Since one certified labor certification application can support only one I-140 petition, what happens if the employer files a new I-140 petition to substitute the employee and the new employee applies for I-485 based on the newly approved I-140 petition? The letter still begs a host of questions and it will remain so until the AC 21 regulation is officially enacted.
