TN By Mail

What happens if a TN extension is requested by mail and the new I-94 does not arrive by the time the current one expires? Once the application is in, are we allowed to stay and/or work until a decision comes through one way or the other?

Yes as long as you timely file, meaning the petition is received by USCIS before or on the expiration date of your I-94 card, you can work with the pending petition for up to 240 days.

I'm a big proponent of mailed in TN petitions; they are now being processed rapidly and CIS will not deny on negligible issues.