Question: I'm on a TN visa and still working for my sponsor, I've got an offer from a different company. They just got the approval notice authorized. My current TN expires in July. Do I need to take ALL the supporting documents again to the USA Consulate in Mexico in order to get a new stamped Visa? Can I start working for the new company without a stamped TN visa?
Answer: If your new company has filed an I-129 petition with USCIS and received an I-797 approval notice for a new TN for you, then you may now start working for them. Otherwise, you will need to wait until the I-129 petition is approved before you may start working. It is not necessary in this situation to obtain a new TN visa stamp. The TN visa stamp serves solely as a “ticket” that enables you to apply for admission to the U.S. If you’re already in the U.S., you don’t need a visa. But if you need to travel outside the U.S., you may need a new TN visa stamp in order to re-enter. There is at least one exception to this rule.
Even though you’ve changed employers, you may use your previously issued TN visa (provided it has not expired) to re-enter the U.S. You’ll also need to present your original I-797 approval notice to the immigration inspectors. A legacy INS Memorandum provides that H-1B, L, O and P visas are valid for re-entry despite a change in employer as long as the beneficiary remains in the same nonimmigrant classification and the visa itself has not yet expired. Although not expressly provided in the Memo, this visa validity rule should equally apply to TN visas.
In the event you wish to or need to apply for a new TN visa stamp, I recommend referring to the relevant U.S. consulate website for more information. Each consulate has its own specific instructions on applying for a TN visa stamp based on an already approved I-129 TN petition. See for example, the U.S. Consulate General in Ciudad Juarez, which requires a complete visa application for the TN visa despite the I-797 approval notice.