If they are legally married, an L-2 spouse is employment-authorized incident to that status, which is a materially better position than the derivative status attached to professional work classifications. Unmarried children under twenty-one accompany as derivatives and may attend school, but they do not gain work authorization.
The principal's category sets the household's options
This is one of the places where the choice of route reshapes a family's finances. A spouse accompanying an L-1 principal holds L-2 status and is employment-authorized incident to status, so she may take a job, join a firm or run a business without the household waiting on a separate permission. That is not true across the board, and a household that has been comparing categories mainly on the principal's convenience should recalculate once a second income is in the picture.
Two limits still apply. The relationship must be a legally recognized marriage, and a common-law partnership does not create derivative eligibility, so a couple in that position should take advice well before travel rather than discovering the gap at a counter. Children remain derivatives only while they are unmarried and under twenty-one, and a child who reaches that birthday mid-assignment needs an independent basis to stay, most often a student route arranged in advance.
Time spent by the family abroad does not extend Thibault's own seven-year ceiling.