Why Do I Owe Self-Employment Tax? A Guide for Brentwood, Tennessee Business Owners Many self-employed people are surprised when they prepare their tax returns and discover that they owe self-employment tax in addition to regular federal income tax. This commonly affects independent contractors, consultants, freelancers, sole proprietors, and other small-business owners throughout Brentwood, Tennessee. Self-employment tax helps fund Social Security and Medicare. The general rate is 15.3% , consisting of 12.4% for Social Security and 2.9% for Medicare. It is generally calculated on 92.35% of net self-employment earnings. Additional Medicare tax may apply at higher income levels. Employees normally split Social Security and Medicare taxes with their employers. Self-employed individuals generally pay both portions because they are treated as both the worker and the employer. This is why a self-employed person may owe considerably more than someone who earns the same amount through...