Under the derivative rules of the connected employment-based category, a child must be unmarried and under twenty-one, so a twenty-two-year-old is not a derivative. He would have to qualify as a principal in his own right. Confirm the program's own family terms on the official page before assuming anything.
Twenty-one is the line the immigrant category draws
The official Gold Card framework, as read on 2026-09-07, routes a successful applicant through a connected employment-based immigrant category, and that category's derivative rules are set by immigration law rather than by the program's page. Those rules admit the principal's spouse and unmarried children under twenty-one, with age calculated under the Child Status Protection Act where a petition's pendency can be subtracted. A son who is already twenty-two cannot be made a derivative by payment.
He could be a principal applicant himself if he meets the program's terms and the connected category's eligibility and admissibility, in which case the per-person processing fee and, on the official page's description, a gift of his own would apply. The Harrison Hot Springs couple should ask the official source in writing how adult children are treated, save the answer with its date, and treat the whole question as one to re-verify before money moves, since the program's terms may change.