TD status does not authorise employment in the United States, and remote work performed from inside the country raises questions that depend on the specific facts. The arrangement should be described to an adviser before it is relied on rather than assumed to be outside the rules.
Describe the work before assuming it is permitted
The relevant facts include where the work is physically performed, who the clients are, who pays, into which account payment is made, and whether the person is holding themselves out as available to United States customers. Households frequently assume that anything billed to a Canadian client is invisible, and that assumption is doing legal work it cannot support. Set out the arrangement in writing and obtain advice on it. Meanwhile, keep the two questions apart: the spouse's Canadian practice is a tax and business matter with its own obligations, while permission to perform work while present in the United States is an immigration matter. TD does permit full-time study, so a dependant who intends to enrol in a course while the household settles is on firmer ground than one who intends to keep earning.
Hypothetical example: An occupational therapist plans a two-year assignment while a partner wants to take an online course and a sixteen-year-old will finish secondary school. The first review should produce a household status chart, passport-expiry calendar, and a clear budget that assumes the dependant cannot take employment merely because the principal has TN classification. Marriage and birth records settle the relationship question; the admission record settles the period granted. If a child will approach age twenty-one during the plan, choose a separate education or immigration path early. A course of study may be possible for a TD dependant, but study is not a substitute for employment permission.