@Truedime
There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative"[QR] in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test.
He cannot be a QC because he is over 18 and not a full time student. He cannot be a QR because his income is over $4300.
See full dependent rules at: https://turbotax.intuit.com/tax-tools/tax-tips/Family/Rules-for-Claiming-a-Dependent-on-Your-Tax-Ret...
