Schedule SE Explained: How Self-Employment Tax Is Calculated

Self-employment tax is 15.3%, and most freelancers assume it applies to every dollar of profit. It doesn't. The IRS taxes only 92.35% of your net profit, and it lets you deduct half of the result from your income tax. Both rules are on Schedule SE, a short form many people let their software fill in without ever reading it.

Knowing the steps lets you check the bill your software hands you. It also tells you why your January tax number came out lower than 15.3% of your profit, and where a W-2 job changes the total.

1.Where the 15.3% Comes From and What It Covers

Self-employment tax is the Social Security and Medicare tax you pay on top of income tax. Employees pay half of it through their paychecks and their employer pays the other half. When you work for yourself, you pay both halves.

The 15.3% has two parts. Social Security is 12.4%, and Medicare is 2.9%. Schedule SE adds them together, and the total lands on Schedule 2 of your Form 1040 with your income tax. The profit it applies to comes from Line 31 of your Schedule C, which the post on Your Schedule C, Line by Line walks through. Every business expense you deduct there lowers the profit Schedule SE taxes.

This applies to sole proprietors, independent contractors, and owners of a single-member LLC (a one-person company the IRS ignores for income tax). Anyone who gets a 1099-NEC or 1099-K for freelance work is usually in this group. Schedule SE is where you report it, and the form is only a page and a half long.

Because the tax starts at the first dollar of profit, the usual income tax tricks don't help here. A standard deduction lowers your income tax, but it does nothing to Schedule SE. Only a higher expense total on Schedule C, which lowers profit, can shrink the base.

2.The Schedule SE Math on $80,000 of Profit

Say a freelance copywriter finishes the year with $80,000 of net profit on Schedule C. The IRS first multiplies that profit by 92.35%. An employer gets to deduct its half of payroll tax, so the IRS shrinks your taxable base by about the same amount to give you a matching break. Then it applies the two rates to the smaller number.

Taxing the full $80,000 at 15.3% would give $12,240. The 92.35% step lowers the bill by $936 before any deduction comes into play. If your software shows a number near $11,300 for this profit, it ran the form correctly.

3.The Half You Get to Deduct

You can deduct half of your self-employment tax when you figure your income tax. In the example, that is $5,652 (half of $11,304). The deduction goes on Schedule 1, and it lowers your adjusted gross income, the income number the IRS taxes after adjustments. You get it whether or not you itemize deductions.

Suppose this copywriter is in the 22% federal bracket. The $5,652 deduction saves about $1,243 of income tax (22% of $5,652). The deduction does not reduce the self-employment tax itself. That stays at $11,304.

Judge Learned Hand, one of the most cited US appeals court judges, wrote in a 1934 tax case, Helvering v. Gregory: "Any one may so arrange his affairs that his taxes shall be as low as possible; he is not bound to choose that pattern which will best pay the Treasury; there is not even a patriotic duty to increase one's taxes." The half-deduction is a plain case. Congress wrote it into the law, and leaving it off your return pays the Treasury $1,243 it never asked for.

Check that the deduction landed on the right form. It belongs on Schedule 1, in the section for adjustments to income, and software fills it in only after Schedule SE has been completed. If you prepare your own return and skip Schedule SE by mistake, the half deduction disappears with it, and your income tax comes out higher than it should.

You owe 15.3% on 92.35% of your profit, then you deduct half of that tax from your income.

4.When You Also Have a W-2 Job

The Social Security part of the tax stops at a yearly limit called the wage base. For 2026 the Social Security Administration set it at $184,500. Your W-2 wages use up that limit first, and only the room left over is available to your freelance earnings. Medicare has no limit. The two cases below use a $60,000 freelance profit, which becomes $55,410 after the 92.35% step.

Option A: Freelancing only

With no W-2 wages, all $55,410 sits under the $184,500 limit. You owe the full 15.3%, which is $8,478.

Option B: A $150,000 W-2 job plus the same $60,000 side profit

Your W-2 wages already used $150,000 of the Social Security limit, leaving $34,500. Only that much of your $55,410 pays the 12.4%, which comes to $4,278. All $55,410 still pays 2.9% Medicare, which is $1,607. The total is $5,885, about $2,593 less than Option A.

5.Three Details That Change the Total

Most returns follow the steps above. These three rules decide the edge cases:

• The $400 minimum. You owe self-employment tax only if your net earnings from self-employment reach $400 for the year. Below that, Schedule SE isn't required.
• The extra 0.9% Medicare tax. Once your combined wages and self-employment earnings pass $200,000 (single filers), an additional 0.9% Medicare tax applies to the amount above that limit. The IRS reports it on Form 8959.
• Losses. If Schedule C shows a loss, you owe no self-employment tax on that business for the year, and the loss does not lower the tax on your other self-employment income.

The IRS publishes all three in the Schedule SE instructions, and they change slowly. The wage base is the one number that rises most years, so check it each January.

6.Setting Aside the Tax Before April

In the $80,000 example, the self-employment tax equals 14.1% of net profit ($11,304 divided by $80,000). Income tax comes on top of that, after the $5,652 deduction and your standard deduction. Because no employer withholds any of it, you pay it yourself through estimated payments, four per year.

Divide the $11,304 by four and you get $2,826 per quarter for the self-employment portion alone. If you move the money into a savings account each time a client pays you, the payment dates stop being a surprise. The full schedule and the penalty rules are in Quarterly Taxes: The Freelancer's No-Panic Guide.

Below the wage base, each extra dollar of profit adds the same amount of tax. Another $10,000 of profit adds about $1,413 of self-employment tax ($10,000 x 92.35% x 15.3%), so a good fall season raises your January payment by a number you can work out in advance.

Self-employment tax follows a fixed order: take 92.35% of profit, apply 15.3% up to the wage base, then deduct half on Schedule 1. Once you can run that order on your own numbers, you can spot a software mistake or a missed deduction in a few minutes.

If you want to see what this tax adds up to on your own profit, the free tax checkup at simplance.org/tax-checkup estimates it from the income and expenses you've already recorded.