First off, I am not a lawyer
Many folks seem to advise against doing anything before I140 approval (& > 180 days after 485 filing), (unless you are considering doing in parallel with a full time job...
)
Next, from
http://www.uscis.gov/files/pressrelease/AC21Intrm122705.pdf
the answer seems to be "yes" ... although it might be related to something totally different that i missed....
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Question 8. Can an alien port to self-employment under INA §204(j)?
Answer: Yes, as long as the requirements are met. First, the key is whether the employment is in a
"same or similar" occupational classification as the job for which the original I-140 petition was filed.
Second, it may be appropriate to confirm that the new employer and the job offer are legitimate
through an RFE to the adjustment applicant for relevant information about these issues. Third, as
with any portability case, USCIS will focus on whether the I-140 petition represented the truly
intended employment at the time of the filing of both the I-140 and the I-485. This means that, as
of the time of the filing of the I-140 and at the time of filing the I-485 if not filed concurrently, the I-
140 petitioner must have had the intent to employ the beneficiary, and the alien must have intended
to undertake the employment, upon adjustment. Adjudicators should not presume absence of such
intent and may take the I-140 and supporting documents themselves as prima facie evidence of such
intent, but in appropriate cases additional evidence or investigation may be appropriate.
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