How much self-employment tax will I pay on $100K income?

The mechanics: the IRS reduces your net profit by 7.65% before applying the SE rate, because a W-2 employee's employer pays that share without it appearing in the employee's wages. On $100K of net Schedule C profit, your net SE income is $100,000 times 92.35%, or $92,350. SE tax of 15.3% on $92,350 equals $14,129.

The breakdown by component: Social Security is 12.4% on the first $176,100 of net SE income (the 2026 wage base). On $92,350, that's $11,451. Medicare is 2.9% on all net SE income with no cap. On $92,350, that's $2,678. Combined SE tax: $14,129. Both are reported on Schedule SE and flow to Form 1040.

One partial offset: you can deduct half of your SE tax ($7,065) from gross income when computing income tax. This is the self-employed analog of the employer's deductible FICA share. It does not reduce SE tax itself, but it lowers the income that income tax runs on, saving roughly $1,500 to $2,000 in income tax depending on your bracket.

SE tax is not withheld. You are responsible for paying it in four quarterly estimated installments (April, June, September, January under IRC §6654). At $100K net profit, combined estimated payments for SE tax and income tax typically run $3,000 to $4,500 per quarter depending on filing status and deductions. Missing or underpaying triggers an underpayment penalty on top of the balance due.

The S-corp angle at $100K: at this income level, an S-corp election typically saves $3,000 to $5,500 per year in SE tax after overhead. You are past the breakeven threshold (roughly $60K to $80K in sustained net profit), but the savings are narrower than at $150K or $200K. Whether the administrative overhead is worth it depends on whether $100K is a floor or a ceiling for your net profit over the next several years.