There are several categories of temporary non immigrant visas which provide for employment authorization. The most frequently used business visa is the B-1 visitor for business. Although admitted into the United States for business, B-1 holders do not have employment authorization and cannot receive a salary or other remuneration in the United States.
Recent changes in the law have affected several non-immigrant categories, including visas for persons with professional credentials, intra-company transferee executives, manages and specialized personnel, persons with extraordinary ability, athletes and entertainers, nurses and prominent business persons.
The H-1B visa is for aliens who have college degrees or the equivalent of a college degree based on their formal education and experience. They must have a job offer from an American employer who needs their professional services. Some of the professions that qualify are engineers, scientists, computer programmers and health care providers. H-1B's may obtain permission to work for up to 6 years in the U.S. However, there is a numerical limit of 65,000 H-1B non-immigrants who may enter each year. There are also H-2 temporary visa's for skilled and semi-skilled workers and H-3 visas for trainees who can prove they will not be taking employment from American workers.
Distinguished artists, actors, athletes, musicians, and other performers as well as individuals with exceptional ability in business may qualify for O or P visas, provided they have a job offer that requires a person of that caliber and the appropriate trade union or peer group association provide a favorable consultation letter.
The L-1 Intra-company transferees must be coming to the United States temporarily to continue to render services in a capacity that is managerial, executive, or involves specialized knowledge.
The intended affiliate employment must be for the same employer or a subsidiary or affiliate of the employer for whom the individual has been continuously employed for one of the last three years outside the U.S. Executives and managers are eligible for up to 7 years, specialized knowledge employees are eligible for up to 5 years.
Other non-immigrant categories for workers include crewman, foreign journalist, exchange visitors on certain government authorized programs and investors or those engaged in international trade from countries which have treaties with the U.S. Employment in each category is authorized for a specific job with a specific employer.
If the applicant is in the United States and is still in legal status it is possible to apply for a change of status while remaining in the United States. Although there are exceptions, applicants who have overstayed the permission to remain in the U.S. or who are not currently in the U.S. must apply for a nonimmigrant visa at an American Consulate abroad. Also, the wife or husband of the applicant and any unmarried children under 21 years of age are eligible for dependent visas.
Remember, this is very general information and should not be used to plan your case. Please seek the advice of an attorney who specializes in this area of law.