Why is the base 92.35% of profit and not all of it?

It mirrors the employee world: employers pay their FICA half on top of wages, so the law lets you knock off the equivalent (7.65%) before computing the tax. It's a small mercy, not a loophole.

Do I still owe self-employment tax if I made very little?

The filing floor is $400 of net self-employment earnings. Above that, SE tax applies from the first dollar, there is no standard deduction for it, which is why small side gigs generate surprise bills.

Does an S-corp election make this go away?

Partially. Only your W-2 salary bears FICA; distributions escape it. Whether the savings beat the payroll overhead is exactly what our S-corp comparison tool computes.

Calculators

Self-employment tax calculator

Employees split FICA with their employer and never see it. You pay both halves, 15.3%, on top of income tax. This itemizes exactly where it goes, and the half you get back as a deduction.

Your numbers

Annual net profit

Revenue minus deductible expenses, Schedule C bottom line.

What the ledger says

Self-employment tax$12,717per year

Social Security portion (12.4%): $10,306
Medicare portion (2.9%): $2,410
Taxed base (profit × 92.35%): $83,115
Deductible half (reduces income tax): $6,358
Effective rate on profit: 14.1%

Estimate, not advice

The formula

SE tax = profit × 92.35% × 15.3%. The 12.4% Social Security part stops at the annual wage base ($176,100 in 2025); the 2.9% Medicare part never stops. Half the total is deductible against income tax.

What this ignores

The 0.9% Additional Medicare surtax above $200k, church-employee rules, and optional farm methods. Income tax is separate, see the quarterly calculator for the whole bill.

Uses 2025 IRS constants (standard deduction $15,000; Social Security wage base $176,100).

Field notes

Why is the base 92.35% of profit and not all of it?: It mirrors the employee world: employers pay their FICA half on top of wages, so the law lets you knock off the equivalent (7.65%) before computing the tax. It's a small mercy, not a loophole.
Do I still owe self-employment tax if I made very little?: The filing floor is $400 of net self-employment earnings. Above that, SE tax applies from the first dollar, there is no standard deduction for it, which is why small side gigs generate surprise bills.
Does an S-corp election make this go away?: Partially. Only your W-2 salary bears FICA; distributions escape it. Whether the savings beat the payroll overhead is exactly what our S-corp comparison tool computes.