Do not assume the original assignment authorizes materially different duties.
Review what the later role involves
Describe the actual continuing work and its relationship to the qualifying knowledge and employer. A customer’s request does not itself expand immigration permission. Hypothetical example: a veterinary-diagnostics reagent maker needs its specialist for validation work before a customer’s launch date.
Use a backwards calendar from the date the knowledge is genuinely needed in the U.S. role. Verify foreign payroll and travel data early, then align technical evidence, contracts and the U.S.
duty description to the same version of the project. Delay or revise the start if a customer scope change turns the work into routine implementation. The timing error seen most often is treating a customer launch date as proof that the specialist is ready for classification.
The relevant question is whether the final assignment uses qualifying knowledge under the documented supervision arrangement. Maintain records for any later extension well before the five-year maximum. Document the final project version and the person supervising it, so an urgent commercial milestone does not mask a material duty change.