Social Security Tax Calculator
Estimate Social Security and Medicare taxes for employees or self-employed income.
How this Social Security tax calculator works
This calculator estimates FICA taxes by applying the current Social Security and Medicare rates to your income. If you choose Employee, it estimates your employee withholding plus the employer match. If you choose Self-Employed, it uses the self-employment framework (including the 92.35% adjustment) and returns an estimated self-employment tax total.
Social Security tax has a wage cap. Medicare tax does not have a cap, and high earners may owe Additional Medicare tax. The calculator makes these rules visible so you can better forecast take-home pay, quarterly taxes, or annual tax planning.
Key rates and limits used
| Tax | Employee Rate | Employer Rate | Self-Employed Equivalent |
|---|---|---|---|
| Social Security | 6.2% | 6.2% | 12.4% (on eligible SE income) |
| Medicare | 1.45% | 1.45% | 2.9% (on eligible SE income) |
| Additional Medicare | 0.9% above threshold | 0% | 0.9% above threshold |
Additional Medicare thresholds
- Single / HOH / Qualifying Widow(er): $200,000
- Married Filing Jointly: $250,000
- Married Filing Separately: $125,000
Employee formula (W-2)
For W-2 wages, this calculator estimates:
- Employee Social Security: min(wages, wage base) × 6.2%
- Employee Medicare: wages × 1.45%
- Additional Medicare: max(0, wages − threshold) × 0.9%
- Total employee FICA: Social Security + Medicare + Additional Medicare
It also shows the employer side (Social Security + Medicare match), which helps estimate total payroll tax burden.
Self-employed formula
Self-employment tax starts with net earnings from self-employment. By rule, 92.35% of net earnings are used as the tax base before applying Social Security and Medicare rates:
- SE taxable earnings: net earnings × 92.35%
- Social Security portion: min(SE taxable earnings, wage base) × 12.4%
- Medicare portion: SE taxable earnings × 2.9%
- Additional Medicare: amount above filing threshold × 0.9%
The calculator also shows an estimate of the “deductible half” of self-employment tax for income tax planning.
Example scenario
Suppose you are a single employee with $120,000 in annual wages. Since wages are below the Social Security wage base, the full $120,000 is taxed for Social Security at 6.2%. Medicare applies at 1.45% to all wages, and no Additional Medicare is due because income is below $200,000. The calculator instantly breaks this into annual and per-paycheck estimates.
Common mistakes this tool helps prevent
- Assuming Social Security tax applies to all wages with no cap.
- Forgetting that Additional Medicare tax uses filing-status thresholds.
- Confusing employee withholding with total payroll cost (employee + employer).
- Ignoring the 92.35% adjustment when estimating self-employment tax.
Important notes
This is an educational estimator, not tax advice. Real-world payroll and tax returns may vary due to pre-tax deductions, multiple employers, railroad retirement systems, clergy rules, household employment, or changing IRS/SSA guidance. For filing decisions, use official instructions or consult a qualified tax professional.