An H-1B nonimmigrant worker may only work for the petitioning U.S. employer and only in the H-1B activities described in the petition. The H-1B nonimmigrant worker may work for more than one (1) U.S. employer, however, each employer must have its own Form I-129, Petition for a Nonimmigrant Worker (H-1B), approved by USCIS.
An H-1B nonimmigrant worker may change H-1B employers without affecting his status, but the new H-1B employer must first file a new Form I-129, Petition for a Nonimmigrant Worker, for the foreign national before he begins working for the new employer. Once a new Form I-129, Petition for a Nonimmigrant Worker, is filed with USCIS, under the H-1B “portability” rules, the foreign national can start working immediately without approval. Contrast this situation to a situation where a foreign national seeks to change his nonimmigrant status from, for example, an F-1 nonimmigrant student status to an H-1B nonimmigrant worker status. In this situation, the foreign national cannot start working for the new employer until the Form I-129, Petition for a Nonimmigrant Worker, has actually been approved by USCIS.
Again, an H-1B nonimmigrant may have what is known as “dual intent”. That is, he may intend to immigrate permanently to the United States while holding an H-1B nonimmigrant visa / status. This is contrary to the “nonimmigrant intent” requirements associated with all but three temporary (nonimmigrant) visa categories (i.e., H-1B, L, and V).
Finally, the U.S. government operates on a fiscal year basis that begins each year on October 1 and runs through the following September 30. For those H-1B workers that are subject to the annual cap of 65,000 nonimmigrant visas (and the additional 20,000 H-1B nonimmigrant visas for foreign nationals who have earned a master’s degree or higher from a U.S. institution of higher education), the earliest date by which an employer may petition for a prospective employee is the April 1 preceding the October 1 beginning of the U.S. government’s new fiscal year. Assuming that the offered position is not an exempt position, the timing of an employer’s H-1B petition is critical. This is because in recent years the H-1B cap has been reached within days of April 1. Therefore, late filing may cause an employer to miss the opportunity to participate in the H-1B program in a given fiscal year.