The calculator uses 2026 federal assumptions: a $184,500 Social Security wage base, a combined employee and employer Social Security rate of 12.4%, a combined Medicare rate of 2.9%, and the 92.35% net earnings factor that applies to self-employment income.

 

Other W-2 wages may reduce the remaining Social Security wage base used in the self-employment tax calculation. For S-Corp wages, employer-side Social Security tax is generally determined separately by each employer, so this calculator uses a simplified estimate.