On October 16, 2008, the USCIS issued a new regulation extending the period of stay for TN visa holders from one year to three years.  TN visa holders may also request extensions of stay of three years.

The category “Professionals Under the North American Free Trade Agreement” is available only to citizens of Mexico and Canada. Under the North American Free Trade Agreement (NAFTA) a citizen of a NAFTA country may work as a professional in another NAFTA country provided that
1) the profession is on the NAFTA list,
2) the alien possesses the qualifications for that profession,
3) the job is a professional one and
4) the alien is going to work for a U.S. employer. The spouse and unmarried, minor children of the principal alien may accompany the alien to the U.S., but they are unable to accept employment in the United States. TN status is temporary.

Canadian citizens are not required to obtain a visa, but instead receive TN status with the Immigration Service at the port of entry. The TN status will only be granted if the period of stay is temporary. The requirements for Mexican citizens are more stringent. The prospective employer must file a labor condition application; and a petition with the USCIS, and after the petition has been approved, the alien must apply for a non-immigrant TN visa at a U.S. Embassy or Consulate in Mexico.

Requirements for Canadians and Mexicans wishing to renew their TN status are not the same. Applications for extension of stay are processed by the USCIS. Canadian citizens have two options. First, they may have their employer file a petition with the USCIS. This option does not require leaving the U.S. Second, Canadians may return to Canada to re-apply at the port of entry with the same documentation that is required for an original application. Mexican citizens must have their employers renew their labor condition application and file another petition with the USCIS in order to extend their stay.