As H-1B physicians are sponsored by their employers, their immigration status is tied to their employment (http://www.physicianimmigration.com/751/h-1b-facts-for-foreign-physicians-part-5-change-of-employment-and-moonlighting/). That is, they can only work for the employer who sponsors the H-1B. Nevertheless, a physician may change jobs provided that the new employer files an H-1B petition on her behalf.
In fact, a physician already in H-1B status may start new or concurrent employment when the prospective employer files a new H-1B petition for them (as opposed to waiting until the petition has been approved). This is called “portability” of the H-1B status. The petition is considered filed when the USCIS physically receives the petition. To qualify for portability, the physician must hold or have held H-1B status, the new petition must be filed before their current authorized stay expires, and they must not have been employed without authorization. If the H-1B physician begins the new job upon filing of the petition, and the new H-1B petition is ultimately denied, the physician is no longer authorized to work in that job.
Of course, in the case of a former J-1 physician who has obtained an IGA waiver (http://www.physicianimmigration.com/674/j-1-physicians-part-2-the-interested-government-agency-iga-waiver-arc-and-va-waivers/), things are different. This physician will be contractually obligated to remain with an employer for three years. In this case, if the physician leaves their job before the end of the three year term, they will violate the terms of their J-1 waiver, unless they can establish the extenuating circumstances as previously describe. As a result, before going to work for another employer, the physician will be required to observe the two-year home residency requirement (return back to home country (http://www.physicianimmigration.com/751/h-1b-facts-for-foreign-physicians-part-5-change-of-employment-and-moonlighting/)).
Concurrent Employment (moonlighting)
There is no limit on the number of concurrent H-1B visas for any employee. Therefore, a physician may work for any number of employers, provided each employer has filed an H-1B on the physician’s behalf. This is even the case for physicians subject to a J-1 waiver commitment. For instance, the ARC waiver program (http://www.physicianimmigration.com/674/j-1-physicians-part-2-the-interested-government-agency-iga-waiver-arc-and-va-waivers/) requires the physician to work 40 hours per week as a primary-care physician at a HPSA facility located in the Appalachian region. Therefore, so long as the physician meets their obligations to the ARC employer, they may work part-time for another employer, provided that the employer obtains the required LCA and H-1B approvals. This is commonly called a “concurrent H-1B.”