Can the customer change supervision after arrival without reassessment?

Have the actual change and applicable process assessed before relying on the revised arrangement.

Keep the evidence current

An old description cannot establish conditions that no longer reflect the placement. Hypothetical example: a Corman Park specialist in a manufacturer's proprietary conveyor control system is transferred on L-1B to commission that system at a U.S. customer's mine.

Three months in, the customer proposes to fold the specialist into its own shift roster, with its supervisor setting hours, assigning unrelated maintenance tasks and completing performance reviews. That change goes to the conditions on which an offsite placement is permitted. The worker may be stationed at a client only where the placement is not essentially labour for hire, where the petitioner rather than the client continues to control and supervise the work, and where the assignment still calls for specialized knowledge of the petitioner's own product or process.

A specialist doing the customer's general maintenance under the customer's supervision fits none of those. The decision belongs to the petitioner, not the customer: either decline the change and document the continued reporting line, or, if the arrangement genuinely must change, have the revised terms assessed for whether an amended petition is required before the new arrangement begins. None of this extends the five-year limit on L-1B time, and it does not retroactively alter the qualifying year of employment abroad within the three years before the petition; those remain fixed facts that a new job description cannot improve.