Is your 18 year old paying for over half his own support? Is he no longer a student? Just because he has a job and some money does not mean he cannot be claimed as your dependent--even though he wants to get stimulus money. Try the IRS interview to see if he CAN be claimed. If he CAN be claimed then he does not qualify to get stimulus $.
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
