It all depends whether or not he provided over half of his own support. With 19K of income, he might well have. If he is not your dependent, you can't claim the credit. If he provided more than half of his own support, you can't claim him. If you did provide more than half, he needs to amend his return so you can claim him. See the support worksheet in the screenshot to help you make the determination.
https://ttlc.intuit.com/replies/7022191
[Edited 2/18/2019 [3:30PM]
