Guide · 8 min read
Self-Employment Tax: More Than Expected
An employee sees only half the Social Security and Medicare bill; the employer pays the rest invisibly. A self-employed person pays both halves and sees all of it at once.
On $80,000 of profit you owe $11,304 of self-employment tax plus $7,527 of income tax — $18,830 in total, an effective 23.5% of profit.
Self-employment tax is Social Security and Medicare, the same two programmes an employee funds through payroll withholding. The combined employee-and-employer rate is 15.3%: 12.4% for Social Security and 2.9% for Medicare.
It is not charged on gross profit. It is charged on net earnings, which is profit multiplied by 92.35% — the adjustment that accounts for the half an employer would otherwise have paid.
The calculation on $80,000
Take $80,000 of profit. Multiply by 92.35% to get $73,880 of net earnings. Apply 15.3% and you get $11,304 of self-employment tax.
Of that, $9,161 is Social Security and $2,143 is Medicare. The Social Security portion is capped by the annual wage base; the Medicare portion is not capped at all.
The deduction nobody mentions
Half of the self-employment tax is deductible against income tax. On $11,304, that deduction is $5,652 — and it reduces the income tax bill, not the self-employment tax bill.
Income tax on $80,000 of profit, after that deduction and the standard deduction, comes to $7,527. Together with the self-employment tax, the total is $18,830.
How the effective rate moves
At $50,000 of profit the total is $10,461, an effective 20.9%. At $80,000 it is $18,830 — 23.5%. At $120,000 it is $32,660 — 27.2%.
The rate climbs because Social Security is capped while income tax is progressive. Above the wage base, the Social Security portion stops growing but the income tax portion keeps climbing. The two effects do not cancel; the effective rate keeps rising.
What it does not include
- State and local income tax. In a state with a 5% rate, the total bill is meaningfully higher.
- The additional Medicare surtax above the high-income threshold.
- Self-employed health insurance, retirement contributions and other above-the-line deductions, which would all reduce the income tax portion.
- Tax credits, which can reduce the bill substantially below what this estimate shows.
Frequently asked questions
Do I owe self-employment tax if I have a day job too?
Yes, on the self-employment income. But if your salary already exceeded the Social Security wage base, that portion is not charged twice — the wage base is shared across both. Medicare has no such cap, so that part is always charged.
Is the 92.35% adjustment permanent?
It has been in place since 1990 and is part of the tax code, not a temporary provision. It exists to put the self-employed person on the same footing as an employer-employee pair, who pay 15.3% on the full wage.
Can I lower this legally?
The self-employment tax itself has few levers — it is a flat percentage on net earnings. The income tax portion responds to retirement contributions, health insurance and business deductions, which is where planning actually pays off.