Quick Answer
To calculate self-employment tax, take your net profit, multiply it by 92.35%, then multiply the result by 15.3%. That is the whole formula for most freelancers. On $90,000 of net profit, the answer is $12,716.60. Social Security (12.4%) stops once your earnings reach the 2026 wage base of $184,500. Medicare (2.9%) never stops, and a further 0.9% applies above $200,000 for single filers. You then deduct half of the tax on Form 1040, which lowers your income tax but not your self-employment tax. The calculator above runs this in your browser, without a sign-up or anything leaving your device.
1. The 15.3% Shock (What Is Self-Employment Tax?)
Most people meet self-employment tax the first time they file as a freelancer, and the number is rarely a pleasant surprise. A client pays you $5,000, you owe income tax on it as usual, and on top of that comes another 15.3%. It feels like a second tax on the same money. In a sense, it is, but it is a different tax with a different purpose.
Who pays what: W-2 vs. 1099
When you work for an employer, Social Security and Medicare taxes, together called FICA, are split down the middle. You pay 7.65% out of your paycheck. Your employer pays another 7.65% on top of your wage, and you never see it on your pay stub. The employer and employee half of FICA are each 6.2% for Social Security and 1.45% for Medicare.
When you work for yourself, there is no employer to carry the second half. You are both. IRC § 1401 therefore imposes the tax on your self-employment income at the combined rate, so you pay both halves:
| Component | Employee half | Employer half | Self-employed (both) |
|---|---|---|---|
| Social Security (OASDI) | 6.2% | 6.2% | 12.4% |
| Medicare (HI) | 1.45% | 1.45% | 2.9% |
| Total | 7.65% | 7.65% | 15.3% |
IRC § 1401(a) and (b): A tax is imposed on self-employment income at 12.4% for old-age, survivors, and disability insurance and 2.9% for hospital insurance.
So the 15.3% SE tax is not a penalty for being self-employed. It is the same payroll tax every worker pays, with the employer's share moved onto you. The money also builds your Social Security earnings record and Medicare eligibility, the same way a W-2 worker's FICA does.
SE tax is not income tax
This is the single most common point of confusion for new freelancers, so here it is plainly:
- Self-employment tax funds Social Security and Medicare. It is calculated on Schedule SE.
- Federal income tax funds general government spending. It is calculated on Form 1040 using brackets, the standard deduction, and credits.
They are two separate calculations on two separate bases. You can owe SE tax and no income tax at all, which happens often when a standard deduction wipes out a low income. You can owe income tax and no SE tax, for example on investment income.
2. Step-by-Step Math: How to Calculate SE Tax
You can use a Schedule SE tax calculator or do it by hand. Either way, the logic is the same, and it only takes two steps once you know your net profit. The scenario: A freelance writer with $100,000 of gross income and $10,000 of business expenses. Net profit on Schedule C is $90,000.
Step 1: Calculate net earnings from self-employment (IRC § 1402)
Net earnings = Net profit × 92.35%
= $90,000.00 × 0.9235
= $83,115.00IRC § 1402(a)(12): In computing net earnings from self-employment, the taxpayer takes a deduction equal to one half of the SE tax rate applied to the earnings. The result is a multiplier of 92.35% (100% − 7.65%).
Step 2: Apply the 15.3% rate
Because $83,115.00 is below the 2026 Social Security wage base of $184,500, both pieces apply to the full amount.
Social Security: $83,115.00 × 12.4% = $10,306.26
Medicare: $83,115.00 × 2.9% = $2,410.34
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Self-employment tax = $12,716.60That is your estimated self employment tax: $12,716.60, or 14.13% of net profit and 12.7% of gross receipts.
Why the 92.35% multiplier exists
An employee's 7.65% employer share is a business expense for the employer. It is never counted as the employee's wages, so no one pays tax on it. If the IRS applied 15.3% straight to a freelancer's profit, that profit would effectively be taxed on the employer's half as well. The 92.35% multiplier fixes that by trimming the base by 7.65%, the way an employer's own payroll tax reduces what is left to tax.
3. The 2026 Wage Base Cap ($184,500) & Additional Medicare Tax
The Social Security wage base
The Social Security wage base for 2026 is $184,500, as announced by the Social Security Administration. The 12.4% Social Security portion applies only to net earnings up to that figure. Once your earnings pass it, the 12.4% stops for the rest of the year. The maximum Social Security portion of SE tax in 2026 is therefore: $184,500 × 12.4% = $22,878.00
The 2.9% Medicare portion has no cap. It applies to every dollar of net earnings, however high.
What this looks like at different incomes
| Net profit | Net earnings (× 0.9235) | Social Security (12.4%) | Medicare (2.9%) | SE tax |
|---|---|---|---|---|
| $90,000 | $83,115.00 | $10,306.26 | $2,410.34 | $12,716.60 |
| $150,000 | $138,525.00 | $17,177.10 | $4,017.23 | $21,194.33 |
| $250,000 | $230,875.00 | $22,878.00 (capped) | $6,695.38 | $29,573.38 |
| $400,000 | $369,400.00 | $22,878.00 (capped) | $10,712.60 | $33,590.60 |
How a W-2 day job changes the cap
The wage base is a combined limit across your W-2 wages and your self-employment earnings. Social Security wages from your job count first, and your SE earnings fill whatever room is left. On Schedule SE, the amount of W-2 wages already subject to Social Security tax reduces the base available for the 12.4% portion.
The 0.9% Additional Medicare Tax (IRC § 1401(b)(2))
Higher earners owe an extra 0.9% Medicare tax on earnings above a threshold. The thresholds are set by statute and are not indexed for inflation: $200,000 for Single/Head of Household, and $250,000 for Married Filing Jointly.
4. The Hidden Relief: The 50% Above-the-Line Deduction
The IRS does not leave you paying both halves with no recognition. IRC § 164(f) lets you deduct half of your self-employment tax when you compute adjusted gross income (AGI). That half corresponds to the employer's share, the part that a company would normally deduct as a business expense.
SE tax = $12,716.60
50% deduction = $12,716.60 × 50% = $6,358.30
AGI = $90,000.00 − $6,358.30 = $83,641.70The deduction appears on Schedule 1 of Form 1040 and is "above the line," which means you get it whether you itemize or take the standard deduction. Crucially, this deduction lowers your income tax, but does NOT lower your self-employment tax (because SE tax is calculated first).
5. Frequently Asked Questions
At what income level do I have to pay self-employment tax?
You owe self-employment tax when your net earnings from self-employment are $400 or more. Because net earnings are 92.35% of net profit, that happens at about $433 of net profit. There is no age exemption and no minimum income-tax liability required.
Do I pay self-employment tax if I have a W-2 day job?
Yes, on your side-business profit. But Social Security wages from your W-2 job count first toward the $184,500 wage base, so your 12.4% Social Security portion may be reduced or eliminated. The 2.9% Medicare portion always applies.
How do I pay my self-employment tax to the IRS?
You calculate it on Schedule SE, report it on Schedule 2 and Form 1040, and pay it through quarterly estimated payments (Form 1040-ES) during the year, with any balance due with your return.
Can business expenses reduce my self-employment tax?
Yes. Deductible Schedule C expenses lower net profit, which lowers the base on which self-employment tax is computed.
Does the QBI deduction (Section 199A) reduce self-employment tax?
No. The Section 199A deduction lowers taxable income for income tax purposes only. Self-employment tax is calculated before it applies.
Santanu Sarma
Economics Researcher & Creator of GetInvoicePDF.com
Santanu specializes in public finance and econometrics, holding an Economics Honors from Bhattadev University. He builds high-precision financial models and calculators to help independent professionals optimize tax compliance.
Disclaimer: This tool and article are for informational purposes only and do not constitute tax or legal advice. 2026 figures reflect IRS Revenue Procedure 2025-32. Always confirm your specific situation with a qualified CPA.
Primary sources used in this guide
- IRS Revenue Procedure 2025-32 (2026 inflation-adjusted brackets, standard deduction, and related figures)
- Internal Revenue Code §§ 164(f), 199A, 1401, 1402, 3101(b)(2)
- IRS Schedule SE (Form 1040), Self-Employment Tax, and instructions
- IRS Form 8959, Additional Medicare Tax
- Social Security Administration, 2026 contribution and benefit base ($184,500)