The number that startles every new freelancer is 15.3 percent. That is the self-employment tax rate, and it comes on top of regular income tax, not instead of it. But here is what softens the blow: the 15.3 percent is not applied to every dollar you earn, and the tax code hands back two meaningful discounts along the way. Once you see the actual math, the bill gets more predictable, and predictable is what you want when you are setting money aside all year.
Understanding the calculation matters for anyone with 1099 income, a side hustle, or a small business, because nobody withholds this tax for you. The IRS explains the basics on its self-employment tax page, and the arithmetic happens on Schedule SE, filed with your Form 1040.
What the 15.3 percent actually is
Self-employment tax is Social Security and Medicare tax for people who work for themselves. Employees split these taxes with their employer: 6.2 percent each for Social Security and 1.45 percent each for Medicare. When you are self-employed, you are both the employee and the employer, so you pay both halves: 12.4 percent for Social Security plus 2.9 percent for Medicare equals 15.3 percent.
That framing matters, because this is not money that vanishes. Your self-employment tax payments earn you Social Security work credits and count toward your future retirement and disability benefits, exactly the way payroll tax does for a W-2 worker.
Step one: it starts with net earnings, not revenue
The tax is figured on your net earnings from self-employment, meaning your business income minus your business expenses, the bottom line of your Schedule C. If you billed clients $60,000 but spent $12,000 on software, supplies, mileage, and insurance, the starting point is $48,000, not $60,000. Every legitimate expense you track lowers this tax as well as your income tax, which is one more reason receipts are worth the effort.
Step two: the 92.35 percent haircut
Here is the wrinkle almost everyone forgets. Before the 15.3 percent rate is applied, Schedule SE multiplies your net earnings by 92.35 percent. Why? An employee’s half of payroll tax is not part of their taxable wages, so the code gives the self-employed a matching adjustment: it removes the equivalent of the employer’s 7.65 percent share before taxing you. In practice, your effective rate on net profit works out to about 14.1 percent, not a full 15.3.
A quick example with round numbers: $48,000 of net profit times 0.9235 is $44,328. That is the amount the 15.3 percent applies to, for a self-employment tax of roughly $6,782. The exact figure will come off your own Schedule SE, but the shape of the math is always the same.
The Social Security portion has a ceiling
The two pieces of the tax behave differently at high incomes. The 12.4 percent Social Security portion only applies up to an annual earnings cap, called the contribution and benefit base, which the Social Security Administration adjusts each year for wage growth. Earnings above the cap owe no Social Security tax. If you also had W-2 wages during the year, those wages count against the same cap first.
The 2.9 percent Medicare portion has no cap at all. And once your total earnings pass $200,000 for a single filer or $250,000 for a married couple filing jointly, an Additional Medicare Tax of 0.9 percent applies to the amount above the threshold. Those thresholds are set by statute and do not adjust for inflation.
The deduction that gives half of it back
The second discount comes at the end: you get to deduct one half of your self-employment tax when figuring your adjusted gross income. It is an above-the-line deduction, so you get it whether or not you itemize. In the example above, roughly $3,391 comes off your income before income tax is calculated. It does not reduce the self-employment tax itself, but it meaningfully trims the income tax stacked on top.
Who owes it, and when to pay
The filing trigger is low: if your net earnings from self-employment reach $400 for the year, you owe self-employment tax and must file a return, even if your total income is otherwise too small to require one. Church employees have an even lower threshold of $108.28 in wages. This is why a modest side hustle can create a filing obligation that surprises people in April.
Because no employer withholds for you, the IRS expects the money through quarterly estimated payments using Form 1040-ES, due in April, June, September, and January. A workable habit for most self-employed people in 2026: move 25 to 30 percent of every payment you receive into a separate tax savings account the day it arrives, covering both self-employment tax and income tax. When the quarterly date comes, the money is sitting there, and the 15.3 percent stops feeling like an ambush and starts feeling like a line item you already handled.
