Self-Employment Tax Explained: The 15.3% and What to Do About It

The first 1099 check is a trap made of good news. Nobody withheld anything, the full amount landed in your account, and it feels like a raise. It isn't. It's a gross number, and somewhere between a quarter and a third of it belongs to somebody else.

The part that surprises people isn't income tax — they expected that. It's the 15.3% that arrives on top of it, before income tax has taken a single dollar.

Where 15.3% comes from

On a W-2 job, 7.65% comes out of your paycheck for Social Security and Medicare and your employer quietly pays a matching 7.65% you never see. The two halves fund the same programs.

Work for yourself and you are both halves. Self-employment tax is "12.4% for Social Security and 2.9% for Medicare taxes" — 15.3% together — and it applies to net earnings from self-employment, meaning profit after business expenses, before any income tax calculation happens at all.

The threshold is low: "You usually must pay self-employment tax if you had net earnings from self-employment of $400 or more." Four hundred dollars. One weekend of freelance work clears it.

The two adjustments that make it less bad

The headline rate overstates the real bite, because of two mechanics almost nobody explains.

First, you don't pay it on all your profit. "Generally, the amount subject to self-employment tax is 92.35% of your net earnings from self-employment." That 7.65% haircut exists so a self-employed person isn't paying payroll tax on the portion an employer would have deducted.

Second, you deduct one-half of the self-employment tax in computing adjusted gross income. It's an adjustment, not an itemized deduction, so you get it whether or not you itemize.

Run it on $50,000 of net profit from a Schedule C:

• $50,000 × 92.35% = $46,175 of net earnings subject to SE tax
• $46,175 × 15.3% = $7,064.78 of self-employment tax
• Half of that — $3,532.39 — comes off your income before income tax is figured
• At a 22% marginal rate, that deduction is worth about $777
• Net cost of the self-employment tax: roughly $6,288, or about 12.6% of the profit

And then income tax runs on top of it. On that same $50,000, income tax in the 12% and 22% brackets plus state tax is what turns "15.3%" into the 25% to 35% set-aside that people who've done this for a while will tell you to use.

Where the rate changes

The Social Security half stops. There's an annual cap — the law sets a maximum amount of net earnings subject to the Social Security portion, and it moves every year with wage growth. Above that ceiling the 12.4% switches off and only the 2.9% Medicare portion continues, with no ceiling at all. The Social Security Administration publishes the current year's figure; look it up rather than trusting a number in an article, including this one.

If you have a W-2 job alongside the freelancing, your wages fill that Social Security cap first, and your self-employment earnings sit on top. High W-2 wages plus a side business can mean the Social Security portion is already exhausted and the side income only carries Medicare tax. Schedule SE handles this if you fill it out honestly, and gets it badly wrong if you don't tell your software about the W-2.

At the top end, an Additional Medicare Tax applies to self-employment income above $250,000 for a married couple filing jointly, $125,000 for married filing separately, and $200,000 for everyone else.

Quarterly estimated payments

Nobody is withholding for you, and the U.S. system is pay-as-you-go. The IRS rule: individuals "generally have to make estimated tax payments if they expect to owe tax of $1,000 or more when their return is filed."

The year splits into four uneven periods, and the due dates do not fall at neat quarter ends:

• January 1 – March 31, due April 15
• April 1 – May 31, due June 15
• June 1 – August 31, due September 15
• September 1 – December 31, due January 15 of the following year

The second period is two months long and the third is three. People who divide the year into equal quarters underpay in June every single time. If a due date lands on a Saturday, Sunday or legal holiday, the payment is on time if you make it on the next business day.

Safe harbors: the number to actually aim at

You don't have to predict this year's income correctly. You have to land inside a safe harbor, and the easiest one is built entirely from numbers you already have.

You generally avoid the underpayment penalty if you owe less than $1,000 after withholding and credits, or if you pay at least 90% of the current year's tax, or 100% of the tax shown on last year's return. If your prior-year AGI was over $150,000 — $75,000 if married filing separately — that last figure rises to 110%.

So: take last year's total tax, multiply by 1.00 (or 1.10 if you're over the AGI line), divide by four, and send that four times. You are protected from the penalty even if this year turns out to be your best year ever. You'll still owe the difference in April, but the penalty doesn't attach.

One more lever, and it's the best-kept mechanic in this whole area: withholding is treated as paid evenly across the year regardless of when it actually came out, while estimated payments are credited to the quarter you made them in. If you or a spouse has a W-2 job, you can fix a whole year's shortfall in November by adding to Step 4(c) of a W-4, and the IRS treats a quarter of it as having arrived in April. A November estimated payment gets no such grace.

What reduces the tax, and what doesn't

Business expenses reduce net profit, and net profit is the base for both self-employment tax and income tax. A legitimate deduction here is therefore worth roughly your marginal income tax rate plus about 14 percentage points — considerably more than the same deduction on a W-2 return.

• The simplified home office method: $5 per square foot of home used for business, maximum 300 square feet, so $1,500 at the top. The space must be used regularly and exclusively for business, and "exclusively" is not a soft word — a desk in the corner of a bedroom that also holds a bed does not qualify.
• Business mileage at the standard rate: 72.5 cents per mile for 2026, up from 70 cents for 2025. Commuting to a regular workplace never counts; driving between job sites does.
• Health insurance premiums for the self-employed, subject to limits.
• The ordinary equipment, software, supplies and professional fees your business actually requires.

Two things that don't reduce self-employment tax, and people assume they do. The qualified business income deduction — up to 20% of qualified business income, available whether or not you itemize — reduces income tax only; it does not touch the 15.3%. And retirement contributions to a SEP-IRA or solo 401(k) reduce income tax without reducing self-employment tax either. Both are worth doing. Neither is a self-employment tax strategy.

Two ways this goes wrong

Setting aside 20% is the most common mistake, and it's a specific one — 20% is roughly what the self-employment tax plus a low income tax bracket costs, so it works until it doesn't. Add state income tax and a 22% federal bracket and 20% leaves you short by thousands. Open a separate savings account, move 30% of every payment into it the day it clears, and never look at the balance as available money. Our side hustle tax guide goes further into the deduction side of this.

The other is skipping the quarterly payments entirely and planning to settle in April. That doesn't just create a penalty; it creates a year where you owe last year's tax and this year's first quarter in the same month. The people who get destroyed by self-employment taxes are almost never the ones who earned too little. They're the ones who spent the withholding.

Set it up this week

1. Find the total tax line on last year's return. Multiply by 1.10 if your AGI was over $150,000, otherwise use it as-is. Divide by four.
2. Open a separate savings account for tax money, and set an automatic transfer of 30% of every client payment.
3. Put the four due dates — April 15, June 15, September 15, January 15 — in your calendar with an alert a week ahead.
4. Pay through IRS Direct Pay or your IRS Online Account. Both are free; card payments carry a processing fee.
5. Track expenses as you go, in anything. A spreadsheet you actually update beats accounting software you don't.
6. Check your state. Most states with an income tax want quarterly estimates too, on their own schedule.

Nobody enjoys sending the government money four times a year for income they've already spent. The alternative is sending it once, all at once, in the same week the next year's first payment is due. (General information, not tax advice.)