An extension of stay can be obtained by the TN1 and his or her family members by returning to Canada and reapplying for admission in the TN classification; they will be given up to a new three-year period of admission at the port of entry or pre-flight inspection center. A second option is to apply for extension of stay in the U.S. Extension of stay requests made in the U.S. must be filed by the employer.

Unlike the H1B, each time a request for extension is made inside the U.S., supporting documentation must be filed providing evidence that the beneficiary meets the educational and licensing requirements for the profession. After receiving all requested documents, ISSS requires two weeks to file the TN1 petition with USCIS. Once received by USCIS, the petition is normally processed in two months. However, unexpected delays do occur. For this reason, please allow USCIS at least three months to process the application before the official extension date of employment commences.