Your plan forks by citizenship: a Canadian may obtain TN at the border and later return on an unexpired I-94 for the unchanged job, but a Mexican needs a TN visa first and you should not plan a same-day SSA walk-in.

Canadian Citizens; Mexican Citizens

If you are a Canadian citizen residing outside the United States, you are not required to apply for a TN visa at a U.S. consulate. You may establish eligibility for TN classification at the time you seek admission to the United States by presenting required documentation to a U.S. Customs and Border Protection (CBP) officer at certain CBP-designated U.S. ports of entry or at a designated pre-clearance/pre-flight inspection station. If you are a Mexican citizen residing outside the United States, you must obtain a visa to enter the United States as a TN nonimmigrant. You should apply for a TN visa directly at a U.S. embassy or consulate in Mexico.

(d)(3)(ii)

The applicant must present documentation sufficient to satisfy the consular officer (in the case of a Mexican citizen) or the Department officer (in the case of a Canadian citizen) that the applicant is seeking entry to the United States to engage in business activities for a United States employer(s) or entity(ies) at a professional level, and that the applicant meets the criteria to perform at such a professional level. This documentation may be in the form of a letter from the prospective employer(s) in the United States or from the foreign employer, and must be supported by diplomas, degrees or membership in a professional organization. The documentation shall fully affirm: The professional activity in which the applicant shall be engaged; the purpose of entry; the anticipated length of stay; the educational qualifications or appropriate credentials which demonstrate that the Canadian or Mexican citizen has professional level status; and the arrangements for remuneration for services to be rendered.

(b)

Temporary entry, as defined in the USMCA, means entry without the intent to establish permanent residence. The alien must satisfy the inspecting immigration officer that the proposed stay is temporary. A temporary period has a reasonable, finite end that does not equate to permanent residence. In order to establish that the alien's entry will be temporary, the alien must demonstrate to the satisfaction of the inspecting immigration officer that his or her work assignment in the United States will end at a predictable time and that he or she will depart upon completion of the assignment.

(g)(1)

An alien may be readmitted to the United States in TN classification for the remainder of the authorized period of TN admission on Form I-94 (see § 1.4), without presentation of the letter or supporting documentation described in paragraph (d)(3) of this section, and without the prescribed fee set forth in 8 CFR 106.2, provided that the original intended professional activities and employer(s) have not changed, and the Form I-94 has not expired.

A; TN chart entry

The following chart lists, by COA code, non-immigrants authorized to work in the U.S. without separate authorization from DHS. The alien's I-94 showing one of the following COAs has employment authorization unless otherwise noted. Form I-94 will not have the DHS employment authorization stamp and the alien may not have an EAD. |TN |Professional businessperson from Canada or Mexico, North American Free Trade Agreement (NAFTA). |

If you are unable or choose not to apply for an SSN using one of the methods above, we recommend you wait 10 days after arriving in the United States to apply for an SSN. This will make it easier for us to verify your DHS documents online. This will also speed up the processing of your SSN application. To complete the application process, you must visit your local Social Security office or Card Center with the required documents within 45 days of starting the process. If you are unable to self-schedule an appointment, please call to make the appointment before visiting.

To prove your identity and work-authorized immigration status, you will need to show us your current U.S. immigration documents and your unexpired foreign passport. You must present your foreign birth certificate if you have it or can get it within 10 business days. Important: All documents must be either originals or copies certified by the issuing agency. We cannot accept photocopies or notarized copies of documents. Your birth certificate or passport may serve as proof of age. However, you must provide at least two separate documents.

We don’t require you to have an SSN before you start working. However, the Internal Revenue Service requires employers to use your SSN to report your wages. While you wait for your SSN, your immigration documents can prove your authorization to work in the United States.

Item 16

Show an address where you can receive your card 7 to 14 days from now. MAILING ADDRESS (Do Not Abbreviate) Street Address, Apt. No., PO Box, Rural Route No. City State/Foreign Country ZIP Code

Whenever any person makes application for a visa or any other document required for entry, or makes application for admission, or otherwise attempts to enter the United States, the burden of proof shall be upon such person to establish that he is eligible to receive such visa or such document, or is not inadmissible under any provision of this chapter, and, if an alien, that he is entitled to the nonimmigrant, immigrant, special immigrant, immediate relative, or refugee status claimed, as the case may be.

Those who need to prove their legal-visitor status—to employers, schools/universities or government agencies—can access their CBP arrival/departure record information online.