When must an individual file additional taxes on self-employment income?

An individual must file additional taxes on self-employment income when net earnings from self-employment are $400 or more. This threshold is established by the Internal Revenue Service (IRS) and indicates that self-employed individuals must pay self-employment tax if their net earnings exceed this amount. Self-employment tax encompasses Social Security and Medicare taxes, which are typically withheld by employers for wage earners. When a self-employed person's net earnings reach $400, it signals the IRS's requirement to file a Schedule SE to report self-employment income and calculate the corresponding tax owed.

In the context of the other options, while net earnings exceeding $200 could imply a requirement to file certain forms, the IRS specifically sets the threshold for self-employment tax obligations at $400. Total income exceeding $1,000 does not directly relate to self-employment tax but instead pertains to income tax filing thresholds for individual tax returns. Lastly, not meeting quarterly estimated payments does indicate potential penalties or additional taxes owed, but it does not establish a direct requirement for filing related to self-employment income, unlike the $400 threshold.