What are the general reasons used for USCIS to deny an I-140 application?
The USCIS appears to dig into the I-140 supporting documentation and develop issues of I-140 denial from these evidence, such as income tax returns, W-2 copies, etc., which can be used to challenge employer’s financial ability to pay, or existence of real permanent job or real business, or legitimate nature of job opening as related to the familial relationship between the employer and the alien, etc.
