No. TD derivative eligibility is for a qualifying spouse and unmarried children under 21; living together alone does not establish spousal eligibility. A relationship described as common-law needs assessment of whether it is a legally valid marriage for U.S. immigration purposes, not merely a Canadian benefits classification.
Plan the partner’s status independently where needed
Do not assume that proof of cohabitation creates a TD route. Identify the legal relationship and the activities each person proposes. TD does not authorize employment, including simply because a job is paid from Canada while performed in the United States. A partner without derivative eligibility needs assessment of an appropriate independent basis; no particular alternative is promised.
Map each household member before making travel or employment commitments. Confirm whether the partner is a legally qualifying spouse, record each child’s age and marital status, and list what each person plans to do in the United States. TD is available to a TN principal’s spouse and unmarried children under 21; cohabitation alone is not enough. A TD spouse or child may study but cannot work in TD status, although employment is possible if that person is otherwise authorized by DHS. Do not treat Canadian common-law terminology or Canadian payroll as permission to perform services while in America.
Hypothetical example: A LaSalle environmental engineer has a qualifying temporary assignment, while an unmarried partner operates a home-staging consultancy and expects to keep serving customers after accompanying the engineer. A shared lease and benefits enrollment do not establish marriage for TD purposes. They should assess the relationship and any independent status before scheduling the move. If they later marry validly, they should still remember that TD itself would not authorize the consultancy work.