Yes, your 18 year old can be claimed as a qualifying child dependent. Since he has over $400 of self-employment income, he is required to file a return himself and pay self-employment tax for Social Security and Medicare. He must say on his own return that he can be claimed as someone else's dependent.
The Premium TurboTax online software is expensive----you might want to use some other free tax software for him
Use this IRS site for other ways to file for free. There are 8 free software versions available from the IRS Free File site
https://apps.irs.gov/app/freeFile/
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
Only income earned from working can be put into his Roth.
**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.**
