How this calculator works
Tax year: 2024. Employee Social Security is 6.2% up to $168,600, and Medicare is 1.45% without a wage ceiling. Additional Medicare is 0.9% above the filing-status threshold and has no employer match. Self-employment mode applies regular combined rates to 92.35% of net profit, with the $400 net-earnings filing threshold. It assumes no concurrent wages, no special farm method and one earner.
Formula
Employee FICA = 0.062 x min(wages,168600) + 0.0145 x wages + 0.009 x max(0,wages - threshold). Self-employment base = net profit x 0.9235; regular rates are doubled.
Worked example
An employee with $60,000 wages pays $3,720 Social Security and $870 Medicare, totalling $4,590. At $200,000 single wages, the total is $10,453.20 + $2,900 = $13,353.20.
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Frequently asked questions
Why can withholding differ from Additional Medicare owed?
Employers start withholding at $200,000 per employee regardless of filing status. Final liability uses the filing-status threshold and combined earnings.
Can I combine wages and self-employment?
This worksheet does not coordinate the shared Social Security wage base. Use Schedule SE for mixed earnings.
Is Additional Medicare deductible as half of SE tax?
No. Only half of regular self-employment Social Security and Medicare tax is shown as deductible here.