Does an employee's seniority for layoff purposes carry over if I buy just the assets?

Generally, yes, if the employee is hired as part of a going-concern asset purchase and continuity of employment applies under the Employment Standards Act. Seniority for layoff purposes is often governed by workplace policy or a collective agreement rather than being a distinct statutory concept on its own, but where an employee's underlying service is treated as continuous under the ESA, that combined service — with the seller and now with you — is generally what any seniority-based policy or agreement should be measured against, not a fresh clock starting at your closing date.

This matters most where you're unionized, since collective agreements frequently build layoff and recall rights directly around seniority, and getting this wrong (treating a long-tenured employee as junior because they "just started" with you) can create real disputes, whether or not a grievance procedure is formally in play. Even in a non-union setting, treating continuing employees as having no seniority can undercut the point of statutory continuity and create fairness and legal risk if it affects who's chosen for a layoff.

Apply seniority-based decisions using an employee's full combined service, not just their tenure since your purchase. A Treadstone business lawyer can help you apply this correctly.