A special office of U.S. Citizenship and Immigration Services (USCIS), called the Office of Fraud Detection and National Security (FDNS) will conduct a site visit for companies with alien workers in H-1B, L-1, or O-1 status. There may be a few red flags to trigger the FDNS to have a site visit. For example, the alien workers may be placed at a location that is different from the U.S. employer’s actual work location. These practice and work location arrangements are often occur with alien workers in the Information Technology (IT) field.

Some U.S. service companies employ many alien workers as "consultant", and assign these consultants to work for their "end client" companies at the client's locations. Because these arrangements can be confusing for USCIS, the FDNS conducts the site visits to confirm that the worksite location explanation on the non-immigrant visa application Form I-129 for H-1B, L-1, or O-1 visa is correct, and that the U.S. service companies are truly the alien worker’s employer.

It is very importance to provide true and accurate information on all H-1B, L-1, or O-1 visa applications. The USCIS' Office of Fraud Detection and National Security is very likely to conduct a site visit if the U.S. employer has previously committed immigration visa fraud. If the FDNS finds the fraud, it will carefully review all subsequent immigration petitions filed by the U.S. employer.