An employee sees a payroll tax deduction on their payslip and assumes that is the cost. It is half of it. The employer pays a matching amount that never appears anywhere the employee sees.
Working for yourself means paying both halves. That is the single largest surprise for people in their first year of self-employment, and it is why a freelance rate matching a previous salary produces meaningfully less take-home pay.
What changed in 2026
- The wage base for the Social Security portion continued adjusting. The cap on that component rises annually.
- Gig platform reporting expanded. More income became reported to tax authorities automatically.
- Estimated payment enforcement stayed active. Underpayment penalties continued to catch people who did not set money aside.
- Entity structure interest grew. More freelancers considered structures affecting how much income is subject to this tax.
What it is and what it applies to
Self-employment tax funds the same programmes as employee payroll tax — retirement and health insurance contributions. The difference is who pays.
|
Employee |
Self-employed |
| Employee portion |
Withheld from pay |
You pay |
| Employer portion |
Paid by employer |
You pay |
| Total borne by you |
Half |
Both halves |
| Visible on a payslip |
Employee half only |
No payslip |
It applies to net business profit — revenue minus deductible business expenses — not to gross revenue. That makes legitimate business deductions doubly valuable, since they reduce both income tax and self-employment tax.
Two structural details soften it. The Social Security component applies only up to an annual wage cap, above which only the health insurance component continues. And half of the self-employment tax is deductible against income tax, roughly mirroring the employer deduction an employer would take.
Those help and do not change the basic arithmetic: your effective rate on business profit is meaningfully higher than an employee's on equivalent wages.
Quarterly estimated payments
Nobody withholds for you, and tax authorities generally expect payment through the year rather than in a lump at filing.
That means quarterly estimated payments covering both income tax and self-employment tax. Underpay and penalties apply, calculated as interest on the shortfall from when each payment was due.
Safe harbour provisions generally protect you from penalties if you pay at least a specified proportion of the prior year's liability, or a specified proportion of the current year's — which makes the prior-year figure a useful anchor when current income is unpredictable.
The practical habit that prevents most problems: set aside a percentage of every payment received, into a separate account, immediately. Estimating that percentage generously is better than the alternative, and it converts a quarterly scramble into a transfer.
Budgeting from revenue rather than profit is the common error. Revenue is not yours; profit after tax is — see quarterly estimated taxes.
Structure affects it
Once profit is substantial, the business structure begins to matter for how much is subject to this tax.
As a sole proprietor, essentially all net profit is subject to it. Certain structures allow profit to be split between salary — subject to payroll tax — and distributions that may not be, which can reduce the total.
That is not free. It requires paying yourself a reasonable salary, which tax authorities scrutinise, plus additional administration, payroll filings, and professional fees. Below a certain profit level the costs exceed the saving, and the threshold depends on your circumstances — see S corporation reasonable salary.
It also has knock-on effects on retirement plan contributions and on other deductions, so it is a decision to model rather than to adopt on a rule of thumb.
Common mistakes
- Budgeting from revenue. Profit after tax is what you have.
- Not setting money aside per payment. Produces a quarterly crisis.
- Missing estimated payments. Penalties accrue as interest.
- Forgetting the deductible half. Reduces income tax.
- Pricing freelance work at a previous salary rate. Ignores both halves plus benefits.
- Adopting a structure without modelling the costs. They can exceed the saving.
- Not tracking deductible expenses. They reduce both taxes.
FAQ
How much should I set aside?
A generous percentage of profit covering income tax plus self-employment tax, adjusted for your bracket and state. Erring high is far more comfortable than erring low.
Does this apply to side income?
Yes, above a modest threshold, even alongside employment. Employment withholding does not cover self-employment tax on separate business income.
Can I reduce it?
Legitimate business deductions reduce net profit and therefore the tax. Structural changes may help at higher income. Neither is a reason to invent expenses.
What about retirement contributions?
Self-employed retirement plans allow substantial deductible contributions that reduce income tax, though generally not self-employment tax — see SEP-IRA vs solo 401(k).
Where to go next
For the payment mechanics, read quarterly estimated taxes. For the structure question, S corporation reasonable salary, and for the deduction that reduces taxable business income, the QBI deduction.
This is general information, not tax advice. Rates, thresholds, and rules change; confirm current figures with a qualified preparer.