TN nonimmigrant visas / status are for Canadian and Mexican individuals who are engaged in activities at a professional level. Canadians do not actually need a TN “visa” as they are “visa exempt”; they may simply enter the United States in a TN nonimmigrant “status”, or change their nonimmigrant status to a TN nonimmigrant status if they are already in the United States in another nonimmigrant status. Activities at a professional level are defined as activities that require “at least a baccalaureate degree or appropriate credentials demonstrating status as a professional.”
A TN nonimmigrant worker may only perform work for a U.S. employer. However, citizens of Canada may qualify for TN nonimmigrant worker status if they are employed by a Canadian employer and seek to enter the United States to provide pre-arranged services in an employer-employee relationship with a U.S. entity (or it may be a contractual relationship, either between a self-employed professional or between the professional’s employer and a U.S. entity).
The TN nonimmigrant worker category is similar in some respects to the H-1B nonimmigrant worker category except there is no statutory limitation on how long a TN professional can stay in the United States, and the TN nonimmigrant worker category generally covers a broader range of job categories than does the H-1B.