Much like the options for an extension of TN visa status, individuals have two options to change TN employers. They can file an I-129 petition by mail, or depart the U.S. and request a new TN in the same manner as they obtained their initial TN visa status.
Filing Options
TN visa workers cannot begin employment with a new or additional employer until they receive authorization from U.S. immigration authorities. 8 CFR 214.6 (i).
TN visa workers can change employers by mail using form I-129 in the same manner as if filing for an extension of status.
Alternatively, they can apply to work for a new employer in the same fashion as they obtained their initial TN, e.g. at the border (if a Canadian citizen), or at the U.S. Embassy/Consulate (if a Mexican citizen). 8 CFR 214.6 (i) (2).
USCBP has stated that Mexican citizens who possess a valid TN visa stamp may change employers at the border by departing the U.S. and presenting to USCBP a support letter for the new employer. AILA CBP Practice Pointer, AILA Doc. No. 16091302 (Sept. 13, 2016). However, in practice this has been an unreliable means of changing employers as USCBP officers at the port-of-entry often contend they are unable to process such changes for Mexican citizens.
Caveat if Filing I-129 Petition
Unlike the H-1B visa category, "portability" is not offered under the TN visa category. This means that individuals cannot work with the new employer under TN status until the I-129 petition is actually approved by USCIS.
As processing of the I-129 petition varies, and can take approximately 2 months, individuals may find it more prudent to seek the change of employer at the U.S. border (Canadian) or Embassy/Consulate (Mexican).
Alternatively, an I-129 petition can be filed via premium processing, which results in a response within 15 days, but USCIS charges an additional fee of $1,225 for this service.
Transfers to Another Location / Entity
A TN visa worker who is transferred to another location by the same U.S. employer to perform the same services need not file a new application for TN status. 8 CFR 214.6 (i) (3).
For example, if the TN worker is transferred to a branch or other office of the employer, a new application for TN status does not have to be filed.
If the TN worker is transferred to a separately incorporated subsidiary or affiliate, a new TN application should be filed.