My son is 24 years old. Not considered a dependent any more?

[KenH1]

Anyone can be your dependent if they meet all 7 of the tests below, regardless of their age.

If he was under 19, or under 24 and a full-time student, then he could still earn over $4050 and be considered a dependent.

His age will likely mean that you won't get any child tax credits, however (unless he's permanently disabled).

https://ttlc.intuit.com/replies/5187060