Do not assume permission transfers automatically between employers. The actual additional or replacement arrangement and applicable process need assessment.
Use the end date and next authorization separately
An available schedule is not permission to work. Identify the next employer, duties and intended period and compare them with the existing status. A smooth commercial handover does not guarantee a matching immigration timeline.
Review current entry procedures before booking travel, and if the employer, the duties, or the assignment changes, ask for a fresh review rather than assuming the original plan still applies. Before travel or productive activity, obtain the final duty allocation, confirm the US or foreign employer, the U.S. entity for which the activity will be performed, and the temporary engagement, and match the work to one listed USMCA profession and its qualification rule. A Canadian citizen may request TN admission at an eligible port of entry or preclearance location, or a prospective employer may file Form I-129, but neither option converts incomplete licensing or certification into permission to practise. Field seasons create their own pressure: an employer that needs someone in the woods for a specific window will resist a slipping start date, so agree the schedule inside the offer rather than around it.