Canadian or Mexican professionals may work for companies in the United States on a temporary basis, under the North American Free Trade Agreement (NAFTA), either as a direct employee or as a management consultant. The maximum period of the initial authorized stay under the TN category is one year, with unlimited one-year extensions.
Under NAFTA there is a specific list of professions, which may qualify for TN category. This list is long and includes computer science, engineering, architecture, economics, and many other professions. A Canadian applicant for a TN status may file an application for admission directly at the United States – Canada border. As for Mexican citizens, the United States employer must first file and obtain approval of a TN petition with a the US Citizenship and Immigration Service (CIS) regional service center before the Mexican citizen may apply for a visa stamp at the U.S. Consulate