Two Dates, and Only One Controls the Job
Every TN engineer carries two expiration dates, and they are easy to confuse. The first is on the TN visa in the passport, the foil a U.S. consulate issued in Mexico. That visa is a travel document. It lets the engineer ask to be admitted at a port of entry, and its validity is set by the State Department's reciprocity schedule for Mexican citizens.
The second is on the I-94 admission record, created by U.S. Customs and Border Protection each time the engineer is admitted in TN status. Under the federal regulation, each TN admission runs for up to three years. The I-94 date, not the visa date, is the one that controls whether the engineer is in status and authorized to work for your company.
The two dates rarely line up. A visa can expire while the I-94 is still valid, and the engineer can keep working until the I-94 date as long as they stay in the U.S. and keep working in the role that was approved. The reverse also happens: a visa with time left on it does not extend an I-94 that is about to run out.
Ask the engineer to download their most recent I-94 from the CBP I-94 website after every entry, and keep a copy in your HR file. Plan the renewal around that date. A passport close to expiry can affect the next admission too, so track the passport date alongside it.
No Lifetime Cap, but Each Renewal Is a Fresh Review
The regulation is plain on the total: "There is no specific limit on the total period of time" a professional may spend in TN status. An engineer can renew for as long as the job, the qualifications and the category still line up.
That does not make renewals automatic. TN is a temporary entry category. The USMCA defines temporary entry as "entry without the intent to establish permanent residence," and the officer reviewing each renewal can ask whether the stay is still temporary. If your company is thinking about sponsoring the engineer for a green card, talk to your immigration attorney before starting that process, because it can complicate later TN renewals.
Each renewal is also judged on the rules in force on the day it is filed. Guidance from USCIS and the State Department has moved more than once since 2025, so a role that was approved three years ago should be reviewed again against the current rules, not assumed to pass.
The Two Ways to Renew
There are two routes, and your attorney chooses between them based on the engineer's travel plans, the visa date, and how much risk of time away from the plant your team can absorb.
| Extension filed with USCIS | New application through a consulate | |
|---|---|---|
| Who files | The employer files Form I-129 for the engineer | The engineer applies for a new TN visa, with the employer's support letter and offer |
| Where the engineer is | Stays in the U.S. | Travels to a U.S. consulate in Mexico, then is admitted at a port of entry |
| Interview | None at a consulate | In-person consular interview |
| Work during the process | With a timely filing for the same employer, work can continue for up to 240 days past the I-94 date while USCIS decides | The engineer is away from the plant for the appointment and the trip |
| Travel | Check with your attorney before any trip abroad while the extension is pending | Travel is part of the route |
| Result | A new I-94 period, but no new visa in the passport | A new visa and a new I-94 at the port of entry |
A third option exists for an engineer whose TN visa is still valid: applying for readmission at a port of entry before the current I-94 runs out, with a new employer support letter. The regulation allows it. Whether it is the right choice depends on the case, which is a question for your attorney.
Sources: 8 CFR 214.6, paragraphs (e) and (h), on the three-year admission, extension of stay and readmission; 8 CFR 274a.12(b)(20), on continued work for up to 240 days with a timely filed extension.
What Changed at the Consulates Since 2025
An engineer who renewed by mail through a consulate's interview waiver in the past will find the process has changed. Three changes from the State Department matter for anyone planning a consular renewal now.
Interview waivers no longer cover TN renewals
The State Department's interview waiver update of 18 September 2025 limits waivers for renewals to B-1/B-2 visas, Border Crossing Cards and H-2A visas. A TN renewal through a consulate now means an in-person interview, so the engineer needs an appointment, not a drop-off.
Apply in the country of nationality or residence
Nonimmigrant visa applicants are generally expected to apply in their country of nationality or usual residence. For a Mexican engineer, that means a consulate in Mexico, and the main variable becomes appointment availability there. Check the State Department's current visa appointment wait times before choosing a date.
Online presence review for TN applicants
From 1 October 2026, the State Department added TN and TD visa applicants to its expanded online presence review, and applicants are asked to set their social media profiles to public. Engineers should hear about this from your attorney early, not at the consulate.
When a Renewal Is Not Just a Renewal
A renewal assumes the same employer, the same job and the same professional category. Some changes during the first admission alter that, and they are easier to handle before the paperwork starts than after.
- New duties or a new title. A promotion that moves the role away from the engineering work described in the original support letter can change the analysis. Have your attorney review the role before the title changes, not at renewal time.
- A new or additional employer. The regulation says employment with a different or additional employer "is not authorized prior to Department approval of the request." A move between related companies should be checked the same way.
- Family members in TD status. A spouse and children hold their own dependent status with their own dates. Track their I-94 dates alongside the engineer's, and ask your attorney how they renew under the route you choose.
A Renewal Plan That Works Backwards
Start from the I-94 date and plan backwards. The points below are starting suggestions to agree with your attorney, not processing times.
Check the dates and the role
Confirm the I-94, visa and passport dates for the engineer and any family members. Compare the engineer's current duties with the original support letter.
Choose the route with your attorney
Decide between a USCIS extension and a consular application, and agree in writing who pays the attorney and government fees for this renewal.
Prepare and file
Your attorney prepares the support letter and the filing. For a USCIS extension, your attorney confirms how early it can be filed. For the consular route, check current wait times and book the appointment.
Confirm and update your records
Get a copy of the approval or the new I-94, and complete Form I-9 reverification on time, following USCIS guidance for your situation.
Who Does What
Your company
Tracks the I-94 dates, keeps the role consistent with the support letter, signs the support letter, decides who pays for the renewal, and handles Form I-9 reverification.
The engineer
Keeps the passport valid, shares each new I-94, completes the DS-160 and attends the interview if the route is consular, and flags any planned travel early.
Your immigration attorney
Chooses the route, prepares the support letter and filing, and confirms the role still fits the professional category under the current rules.
Put the I-94 date on the calendar, not the visa date. Start about nine months out, choose between a USCIS extension and a consular application with your attorney, and plan for an in-person interview if the engineer renews through a consulate. Changes to the role belong in front of your attorney before they happen.
This article is informational only. ACE & Bridgewell is not an immigration law firm and does not provide legal advice. TN visa requirements can change and individual circumstances vary. Always work with a qualified immigration attorney for guidance specific to your situation.
