Adjustment of status portability is a creation of the American Competitiveness in the 21st Century Act (AC21) Pub. L No. 106-313, 114 Stat. 1251 (October 17, 2000), which amended Section 204(j) of the Immigration and Nationality Act.

This AC21 law allows employees to accept a job that is in the same or similar occupational classification as the job on which the I-140 petition was based, if an adjustment of status application (I-485) has been pending for 180 days or more.  The underlying I-140 petition remains valid, even though the applicant has changed jobs.

The determination that the new job is in the same or similar occupational classification is made by

1) Comparing the job duties in the original ETA 750 or 9089 or I-140 with the job duties of the new job;
2) Comparing the DOT or SOC codes of the I-140 with those of the new position;
3) Comparing the previous and new wage to see if there is a substantial discrepancy.

Jobs with very different responsibilities may still fall under the same occupational classification because the substantive knowledge required for those jobs can be identical.

If the originally intended employer withdraws the previously approved I-140 on or after the I-485 has been pending for 180 days, the I-140 remains valid. If the applicant has not already submitted evidence of the new qualifying offer of employment, the USCIS officer should issue a notice of intent to deny.

An applicant can “port” before the 180 days have passed because there is no requirement that the applicant ever have been employed by the original petitioner while the I-485 was pending. The only requirement is that there was an intent to accept that employment at the time that the adjustment of status application was filed.