Sorry they need to file their own returns and pay self employment tax on a 1099NEC even if they don't owe any regular income tax on it. Be sure on their return they check the box that they can be claimed as a dependent on someone else's return. Putting it in an IRA won't avoid the SE tax. Buts it's a good idea. For an IRA contribution. If you only have self-employment income you can only contribute up to your net profit reduced by the deduction allowed for one-half of your self-employment taxes. See IRS publication 590 http://www.irs.gov/pub/irs-pdf/p590a.pdf
Does a dependent need to file a tax return?
Do I need to file my own taxes if I'm a dependent?
Online is only good for 1 return per account. But you can use the same email address for 5 accounts. How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...
Or go to the IRS Free File programs
Free File: Do your Federal Taxes for Free | Internal Revenue Service
The Desktop CD/Download program can do unlimited returns and efile 5.
