Money reported on a 1099NEC is "non-employee compensation" and is subject to self-employment tax for Social Security and Medicare since no tax was withheld for SS or Medicare from your son's pay. Even though he is below the threshold to owe ordinary income tax, he owes self-employment tax.
https://turbotax.intuit.com/tax-tools/calculators/self-employed/
https://ttlc.intuit.com/community/self-employed/help/how-do-i-report-income-from-self-employment/00/...
https://ttlc.intuit.com/community/self-employed/help/what-is-the-self-employment-tax/00/25922
https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/enter-self-empl...
**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.**
