The 1994 North American Free Trade Agreement (NAFTA) facilitates travel to and employment in the US of certain Canadian and Mexican workers. It creates a visa category known as "TN" for eligible professionals from these two countries. There is no annual limit on the TN admissions from Canada. Mexican TN professionals may not exceed 5500 admissions per year. TN employment must fall within the Schedule of NAFTA professions (e.g. teacher, management consultant, engineer, et. al) and the TN employee must possess the credentials required. TN status allows unlimited multiple entries to the US for the period of services required by the US employer, for a maximum of one year, extended indefinitely as long as the temporary purpose of the employment continues.
Canadians may apply for the TN classification directly at the Port of Entry. Documentation must include proof of Canadian citizenship, proof of the employee's credentials, and documentation from the US employer of the nature and duration of the employment and wages in the US.
In contrast, Mexicans must be beneficiaries of an I-129 petition filed by the prospective US employer in the US and approved by the Immigration Service.
Family members of TN professionals enter the US in "TD" status. TD non-immigrants may be students in the US, but they are not authorized for employment.
TN Canadians may change employers in one of two ways: 1) by filing Form I-129 with the Immigration Service while still in the US or by departing the US and presenting revised documentation relating to the new employment at the port of entry. Mexicans may change employers only by filing Form I-129 with the Immigration Service.
A TN professional must maintain the intent to depart the US at the conclusion of the approved TN employment and not to intend to establish permanent residence in the US. Of course eligible TNs are not prohibited from changing from TN status to another nonimmigrant category that permits dual intent and subsequently petitioning for permanent residence and adjustment under the new classification.