A factual description of the position, pay, and intended period, together with the identity and qualification records the case will rely on. Any material difference between the offer, an agency contract, and the proposed letter should be resolved first.
Let each party confirm only what it actually knows
The applicant is the right source for credential and identity records; the employer is the right source for confirming the actual working arrangement. If a staffing agency and an end client describe the assignment differently, ask them to reconcile it before anything is finalized. Keep dated versions so the current one is clear — no letter can substitute for an unconfirmed position or an unverifiable credential.
Before drafting, assemble citizenship proof, the selected USMCA profession's required credential, and final job terms. An employer letter or contract must evidence the arranged professional engagement, whether the employer is American or foreign; it should identify duties, duration, compensation, and the real employing arrangement. Canadian or Mexican citizenship is mandatory. A frequent error is allowing counsel, the candidate, and the employer to rely on different position versions. Reconcile factual conflicts before anyone signs.
Hypothetical example: a Windsor pharmacist receives an offer to review medication-safety reports for a Michigan health contractor. The contractor first supplies a generic analyst template that omits pharmacy duties and names an outdated start date. He obtains his passport, pharmacy degree, and licence records, while the employer corrects its letter and underlying contract to match the actual assignment. The finished package shows what each source can reliably prove without turning the applicant into the author of the employer's facts.