Read the general life across the border overview
A four-year assignment and a child who is nineteen are two calendars that will not stay aligned. Dependent status depends on the child's own facts on the day they are assessed, not on the parent's approval period. Before agreeing to a multi-year plan, write down the dates and ask which age rules apply to which category.
Write the dates before the plan
Record each child's date of birth, marital status, and the day they would reach 21 measured against the requested validity period. TD status is available to a spouse and to unmarried children under 21; it permits study and does not authorize employment, and an unpaid activity is reviewed on its specifics rather than covered by any blanket rule about volunteering. E and L qualifying dependent spouses are employment-authorized incident to valid status with proper I-94 evidence; children are not covered by that same rule. Note which member of your household each of those sentences applies to.
The birthday does not wait for the extension
Hypothetical example, an illustration only and not a description of any local family: a parent accepts a role expected to run four years, and the older child turns 21 in the third year. The household assumes that extending the parent's status extends everyone's. It does not follow automatically — a derivative depends on the child qualifying in their own right at that time. Ask now what options a young adult might have in their own name, what lead time each would need, and what would have to be true months before the birthday rather than after it.
Ask which age rules apply, and to what
Age protection provisions are category-specific. Rules that can matter to a child in an immigrant category do not transfer to a nonimmigrant derivative, and an extension in the parent's category is not an age rule at all. Ask the person reviewing the file which framework applies to your situation, what date each is measured from, and what evidence would be needed. Keep school enrolment, leases and return flights on a separate list: those commitments are consequences of the immigration dates, and they never extend an authorized stay.
What else is on your mind?
Is a matching job title enough for TN?Can years of experience replace a degree for TN?Can my own U.S. company employ me under TN?Can my spouse work if I hold TN status?Editorial source review: 2026-09-07. General preparation guidance, not an individual assessment.