Use the final genuine engagement and explain material changes where relevant.
Keep the offer current
Do not preserve an obsolete compensation description because it produces a more favourable conversion. Review whether any other terms or duties changed and coordinate the lawful start using the actual record.
Freeze the application record only after the employer confirms the final currency, base pay, benefits, duties, worksite, and proposed start. Compare the revision against every draft letter and form, replace obsolete versions, and retain a short explanation if the change is material or could look inconsistent. Recheck the classification rather than assuming only the numbers changed: TN requires a Canadian or Mexican citizen performing prearranged work in a listed USMCA profession, with that profession’s own qualifications and no self-employment. A Canadian can generally present the finalized package at a port of entry or have the employer pursue Form I-129 where suitable. The avoidable mistake is travelling with an attractive old conversion while the signed engagement now says something different.
Hypothetical example: A Larouche accountant receives a revised offer after the employer changes a Canadian-dollar allowance to a U.S.-dollar reimbursement and moves the starting date. Before scheduling travel, he obtains a newly signed support letter, verifies that the accounting duties and duration remain accurate, and marks the earlier calculation as superseded. He also waits for any credential assessment needed for the Accountant category instead of treating the pay amendment as the only timing issue.