The self-employment tax rate of 15.3% comprises two components:
- Social Security tax - 12.4% (applied to net earnings up to a certain limit).
- Medicare tax - 2.9% (applied to all net earnings, with an additional 0.9% for high earners).
The self-employment tax is based on net income from self-employment, not gross income.
Thus, the correct answer is:
Social security tax and Medicare tax on net income from self-employment.