Taxpayer asks: Since the self-employment tax rate is 12.4 percent, why do I have to pay 15.3%? taxgirl says: Self-employment tax, sometimes called SE tax, is a tax consisting of Social [entity display="Security" type="section" active="true" key="/security"]Security[/entity] and Medicare taxes for those who work for themselves. It’s the equivalent of the total of Social [entity display="Security" [...]