Then the US company needs to file the L1B petition for you on form I-129.
The employer in the US must establish you have "specialized knowledge" which gives you proprietary information specific to the company. The USCIS has given a guidance memo on what it means to have specialized knowledge and please refer to page 6 of this link
special knowledge, which is knowledge of the petitioning employer’s product,
service, research, equipment, techniques, management, or other interests and its
applications in international markets that is demonstrably distinct or uncommon in
comparison to that generally found in the particular industry or within the petitioning
• advanced knowledge, which is knowledge or expertise in the organization’s specific
processes and procedures that is not commonly found in the relevant industry and is
greatly developed or further along in progress, complexity and understanding than
that generally found within the petitioning employer.
It is very highly recommended that your US employer retain an experienced immigration attorney to prepare the petition and support letter so that it is very clear you meet the standards. Denials of L1B visa petitions are very high.
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