Derivative eligibility is limited to unmarried children under twenty-one, so a birthday during a long process can remove a child from the case. The Child Status Protection Act can preserve eligibility in defined circumstances, and it is technical enough that it should be assessed at the outset rather than when the birthday approaches.
Calculate the birthday against the timeline first
EB-5 timelines run in years, and a child who is seventeen when the plan begins may not be a child when it concludes. The consequence is severe: an aged-out son or daughter is not simply delayed but is outside the case, and needs an independent basis to be in the United States at all. The Child Status Protection Act addresses part of this by allowing certain periods to be subtracted from the child's biological age, and it depends on how the case proceeds and on prompt action once a visa becomes available.
It is not a guarantee and it is not something to work out from a summary. Hypothetical example: a family from Saint-Joachim-de-Shefford begins a project with a daughter aged nineteen and eight months, assumes she is comfortably inside the limit, and does not raise her age with anyone until the second year. The right moment to model this is before the investment, using the child's date of birth and a realistic view of processing times, so that an alternative such as a student route can be arranged deliberately rather than in an emergency.