How to Deduct Half of Self-Employment Tax on Form 1040: Worked Example

To deduct half of your self-employment tax, run the Schedule SE calculation on your net business profit, then carry 50% of the resulting tax to Schedule 1 (Form 1040), Line 15. The mechanics: take net profit from Schedule C (Line 31) or Schedule F (Line 34), multiply by 92.35% to get your adjusted net earnings, apply the 15.3% self-employment tax rate, and take half of that figure as your above-the-line deduction. It lowers your adjusted gross income without lowering the self-employment tax itself. The deduction is authorized by 26 U.S.C. § 164(f), which lets you write off one-half of the taxes imposed by § 1401.¹

Who Can Take It

If you owe self-employment tax, you get the deduction. There is no income test, no itemizing requirement, no separate election. Self-employment tax applies once your net earnings from self-employment reach $400 in a calendar year, so sole proprietors, independent contractors, freelancers with side income, and general partners with a distributive share of partnership income all qualify. A part-time gig clearing $400 in profit triggers the tax and the deduction together.

One boundary. Members of recognized religious groups that have existed continuously since December 31, 1950, and are conscientiously opposed to insurance benefits can apply for exemption from self-employment tax using Form 4029.² If your exemption is approved, you don’t pay the tax, so there is nothing to deduct.

How to Calculate the Deduction

The calculation mirrors what happens for a W-2 employee, whose employer share of payroll tax isn’t part of taxable wages. To get you to the same place, the IRS strips that phantom employer share off the top before applying the rate.

Start with your net profit. On Schedule C, that’s Line 31; on Schedule F for farming income, that’s Line 34.³ Multiply by 92.35% (0.9235). The result is your net earnings from self-employment for tax purposes.⁴

Apply the 15.3% self-employment tax rate to that adjusted figure. The rate breaks into 12.4% for Social Security and 2.9% for Medicare.⁵ The total goes on Schedule SE, Line 12. Half of that is your deduction, calculated on Line 13 and then transferred to Schedule 1, Line 15.⁶

The Social Security Wage Base

The 12.4% Social Security piece only applies up to the annual wage base, which is $184,500 for 2026.⁷ Adjusted net earnings above the cap are subject only to the 2.9% Medicare portion. Schedule SE splits the calculation for you when your earnings exceed the base, and your deduction reflects the blended total.

The Additional Medicare Tax Is Not Deductible

This is where higher-earning self-employed taxpayers often go wrong. An extra 0.9% Medicare surtax applies to self-employment income above $200,000 for single filers, $250,000 for joint filers, and $125,000 for married filing separately.⁸ Section 164(f) explicitly excludes this surtax from the deduction.¹ You calculate the Additional Medicare Tax on Form 8959 and pay it with your return, but nothing about it feeds into Line 13 on Schedule SE. When you build the Line 13 figure, use only the § 1401 tax at the 15.3% rate.

A Worked Example

Say your Schedule C shows $100,000 in net profit. Multiply by 92.35% to get $92,350 in adjusted net earnings. Self-employment tax is $92,350 × 15.3% = $14,129.55. Half of that, $7,064.78, goes on Schedule 1, Line 15. You still owe the full $14,129.55 in self-employment tax, but your income tax is now calculated on roughly $7,065 less of income.

Where It Goes on Your Return

Line 13 of Schedule SE moves to Schedule 1 (Form 1040), Part II, Line 15, labeled “Deductible part of self-employment tax.”⁹ Schedule 1’s total adjustments then flow to Form 1040, Line 10, reducing AGI before you apply either the standard or itemized deduction.

Because this is an above-the-line adjustment, you get it whether or not you itemize. A lower AGI can also change other numbers on the return: eligibility for the Earned Income Tax Credit, phase-out ranges for education credits, the floor for deductible medical expenses, and the premium tax credit for marketplace coverage all key off AGI. The size of the deduction is modest, but if you sit near a phase-out threshold it can move you across.

Building It Into Quarterly Estimates

No one is withholding taxes from your income, so the IRS collects through quarterly estimated payments covering both income tax and self-employment tax. When you fill out the Form 1040-ES worksheet, subtract the projected half-of-SE-tax deduction from expected AGI so you’re not overpaying through the year.¹⁰

The 2026 quarterly deadlines:

First quarter: April 15, 2026
Second quarter: June 15, 2026
Third quarter: September 15, 2026
Fourth quarter: January 15, 2027

You can skip the January 15 installment if you file your 2026 return and pay the balance in full by February 1, 2027.¹⁰

To avoid an underpayment penalty, meet one of the safe harbors: owe less than $1,000 when you file, pay at least 90% of your current-year tax liability, or pay at least 100% of last year’s total tax. If your prior-year AGI exceeded $150,000 ($75,000 if married filing separately), the last threshold rises to 110%.¹¹ Self-employment income tends to be uneven from quarter to quarter, so the prior-year safe harbor is often the simplest benchmark to hit.

1
Office of the Law Revision Counsel. 26 USC 164 – Taxes
2
Internal Revenue Service. Application for Exemption From Social Security and Medicare Taxes and Waiver of Benefits (Form 4029)
3
Internal Revenue Service. Schedule C (Form 1040) – Profit or Loss From Business
4
Internal Revenue Service. Topic No. 554, Self-Employment Tax
5
Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
6
Internal Revenue Service. 2025 Schedule SE (Form 1040)
7
Social Security Administration. Contribution and Benefit Base
8
Office of the Law Revision Counsel. 26 USC 1401 – Rate of Tax
9
Internal Revenue Service. Schedule 1 (Form 1040) – Additional Income and Adjustments to Income
10
Internal Revenue Service. Estimated Tax for Individuals (Form 1040-ES)
11
Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty