Start with the proposed U.S. employment or assignment letter, proof of citizenship, and evidence of the qualifications for the identified profession. Where several group entities appear, supporting documents should make the actual employment arrangement understandable. A Canadian employment history does not replace evidence about the U.S. role.
Resolve the entity and signature trail
As a practical preparation step, list the names on the contract, support letter, payroll instructions, and organization chart. Explain legitimate differences rather than silently choosing whichever name appears easiest. Ask the signatory to verify duties, duration, and pay arrangements with the receiving manager.
Keep the final version dated and retain superseded drafts for internal reference. A corporate chart can clarify relationships, but it should not bury the professional duties or suggest that corporate affiliation is sufficient for TN. Resolve the entity and signature trail before anything is drafted, since group transfers generate documents from several companies and the inconsistencies are easy to create and awkward to explain.
Establish which legal entity is the proposed U.S. employer, in what jurisdiction it exists, and who has authority to sign on its behalf. Then check that every document names that entity consistently: the offer or assignment letter, the support letter, the description of duties and any internal approval.
Where a document was issued by the Canadian company about a U.S. position, note why and whether it should be reissued. Group companies frequently share letterhead, addresses and personnel, and a letter signed by someone whose authority relates to a different entity is a defect that a reader will notice before anyone internally does.