How Schedule SE Self-Employment Tax Is Calculated
Self-employment tax is the Schedule SE equivalent of FICA. W-2 employees pay 7.65% employee FICA. Their employer pays a matching 7.65%. Self-employed workers pay both halves: the combined 15.3% rate. The calculation follows four steps.
| Step | Calculation | 2025 Values |
| 1. Net SE Income | Gross SE income minus deductible business expenses | Your Schedule C net profit |
| 2. SE Tax Base | Net SE income × 92.35% | 92.35% = 1 minus 7.65% |
| 3. Social Security Tax | SE base × 12.4% (up to $176,100) | Max SS SE tax: $21,836.40 |
| 4. Medicare Tax | SE base × 2.9% (no cap) | No ceiling |
| Total SE Tax | SS tax + Medicare tax | Line 12 on Schedule SE |
| SE Deduction | Total SE tax × 50% | Schedule 1, line 15 (above-the-line) |
Why 92.35%?
The 92.35% factor (which equals 1 minus 7.65%) is the IRS adjustment that reflects the employer-equivalent share of FICA. W-2 employees pay only the employee 7.65% and do not pay income tax on the employer's matching contribution. Self-employed workers pay both halves. Applying the 15.3% rate to only 92.35% of net income prevents SE tax from applying to the portion that represents the employer's share. Without this adjustment, self-employed workers would pay SE tax on the portion of earnings that would effectively represent their own employer contribution.
2025 Schedule SE Social Security Wage Base: $176,100
Social Security SE tax stops once the SE tax base reaches $176,100 for 2025 (Schedule SE, line 7). For 2026, the wage base rises to $184,500, making the maximum Social Security portion $22,878.00. If your net SE income is $200,000, the SE tax base (after 92.35% adjustment) is $184,700. For 2025, Social Security tax applies on $176,100 of that: $21,836.40. Medicare tax applies on the full $184,700: $5,356.30. Total SE tax: $27,192.70.
The wage base is the same limit that applies to W-2 Social Security withholding. For self-employed workers who also have W-2 wages, the W-2 wages count first against the $176,100 limit. If W-2 wages alone exceed $176,100, no Social Security SE tax applies on the SE income. Medicare SE tax still applies on all SE earnings.
The SE Tax Deduction
You deduct 50% of total SE tax on Form 1040, Schedule 1, line 15. This deduction reduces your adjusted gross income. It does not reduce SE tax itself. It exists because employers can deduct their FICA matching payments as a business expense. The SE deduction provides parallel treatment for self-employed workers. It reduces the federal income tax you owe on your SE income. On $10,000 of SE tax, the deduction is $5,000. At a 22% income tax rate, that $5,000 deduction saves $1,100 in income tax.