
Quoting
8 CFR Sec. 214.6 - Canadian and Mexican citizens seeking temporary entry to engage in business activities at a professional level.
(e) Procedures for admission for a citizen of Canada or Mexico - A citizen of Canada or Mexico who qualifies for admission under this section shall be provided confirming documentation (Form I-94) and shall be admitted under the classification symbol TN for a period not to exceed one year. Form I-94 shall bear the legend "multiple entry". The fee prescribed under 8 CFR 103.7(b)(1) shall be remitted by Canadian Citizens upon admission to the United States pursuant to the terms and conditions of the NAFTA. Upon remittance of the prescribed fee, the TN applicant for admission shall be provided a Department-issued receipt (Form G-211, Form G-711, or Form I-797).
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(g) Readmission
(1) Canadian citizens. A Canadian citizen in this classification may be readmitted to the United States for the remainder of the period authorized on Form I-94, without presentation of the letter or supporting documentation described in paragraph (e)(3) of this section, and without remittance of the prescribed fee, provided that the original intended professional activities and employer(s) have not changed. If the Canadian citizen seeking readmission to the United States is no longer in possession of a valid, unexpired Form I-94, and the period of initial admission has not lapsed, he or she shall present alternate evidence in order to be readmitted in TN status. This alternate evidence may include, but is not limited to, a Service fee receipt for admission as a TN or a previously issued admission stamp as TN in a passport, and a confirming letter from the United States employer(s). A new Form I-94 shall be issued at the time of readmission bearing the legend "multiple entry".
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(j) Spouse and unmarried minor children accompanying or following to join.
(1) The spouse of unmarried minor child of a citizen of Canada or Mexico admitted in TN nonimmigrant status shall be required to present a valid, unexpired nonimmigrant TD visa unless otherwise exempt under Sec. 212.1 of this chapter.
(2) The spouse and dependent minor children shall be issued confirming documentation (Form I-94) bearing the legend "multiple
entry". There shall be no fee required for admission of the spouse and dependent minor children.
(3) The spouse and dependent minor children shall not accept employment in the United States unless otherwise authorized under the Act.