All excellent responses. One potential work-around which is becoming a better and better option is to file a petition with USCIS rather than apply in the first instance at the "border."
If I recall correctly, a petition can only be filed with USCIS for a TN if the individual in question is already outside of the US.
Ie, if you are currently within the US on a TN, and looking to switch jobs, you can not file for a new status with USCIS; your options are either to leave the country and apply at a POE, or leave the country, and only then petition with USCIS.
Is this incorrect? Can a current TN holder petition USCIS for a new TN while still within the US?
Going through this right now! Applying for a new TN through change of employer (COE) while residing in the US. I was given the option to fly back and forth to apply at the border, but figured this would be the safest (and lowest friction) option.
However, it's been a slow process, especially with having received word of USCIS requesting additional evidence from my first application.
Does that issue you a new TN (with a 3 year term), while maintaining your status with the previous employer, or terminate your status with your previous employer, with validity only matching the previous expiration date?
Ie, if you are currently within the US on a TN, and looking to switch jobs, you can not file for a new status with USCIS; your options are either to leave the country and apply at a POE, or leave the country, and only then petition with USCIS.
Is this incorrect? Can a current TN holder petition USCIS for a new TN while still within the US?