How the Self-Employed Tax Calculator works
Updated November 2026
Why self-employed tax has two parts
When you work for yourself, you pay both halves of the Social Security and Medicare tax that an employer and an employee normally split. That combined charge is the self-employment tax. On top of it, your profit is also ordinary income, so federal income tax applies to it as well. This calculator adds the two parts together and splits the total into the four quarterly payments the IRS expects during the year.
The math, in plain words and steps
Step 1: net earnings. Multiply your net profit by 92.35 percent. That is the share of profit the IRS treats as earnings for self-employment tax, the same factor printed in the Form 1040-ES worksheet.
Step 2: self-employment tax. Take 12.4 percent of net earnings for Social Security, but only up to the 2026 wage base of $184,500. Wages from a job count against that base first. Add 2.9 percent of all net earnings for Medicare, with no cap. If your combined wages and net earnings pass $200,000 filing single, or $250,000 filing jointly, add 0.9 percent on the part above the line.
Step 3: taxable income. Start with your profit. Take off half of the self-employment tax (the part the IRS treats as the employer half), the 2026 standard deduction ($16,100 single, $32,200 married filing jointly), and the simplified QBI deduction of 20 percent of profit. If the result is below zero, taxable income is zero.
Step 4: income tax and total. Run the taxable income through the 2026 federal brackets for your filing status. Add the income tax to the self-employment tax for the total, and divide by 4 for each quarterly payment.
A worked example
Take the numbers this calculator opens with. A single filer with net self-employment profit of $80,000 and no W-2 wages.
Step 1: $80,000 x 92.35 percent gives net earnings of $73,880.00. Step 2: Social Security is 12.4 percent of $73,880, which is $9,161.12. Medicare is 2.9 percent, which is $2,142.52. Combined earnings are under $200,000, so the extra Medicare tax is $0. Self-employment tax totals $11,303.64. Step 3: half of that tax is $5,651.82. Taxable income is $80,000 - $5,651.82 - $16,100 standard deduction - $16,000 QBI deduction, which is $42,248.18. Step 4: the 2026 single brackets tax that at $4,821.78. The total federal tax is $11,303.64 + $4,821.78 = $16,125.42, an effective rate of 20.16 percent of profit. Take-home after federal tax is $63,874.58, and each quarterly payment is $4,031.36.
How to read your result
The total is the headline: what to set aside across the year for federal tax. The effective rate turns it into a rule of thumb for each invoice: at 20.16 percent, about 20 cents of every profit dollar belongs to the IRS. The quarterly payment is the amount for each Form 1040-ES due date. Change the profit and watch the rate climb, because the standard deduction and the Social Security cap matter less as income grows. If you want the rules behind the dates and the safe harbor options in depth, the 1099 Tax Playbook (CA$27.99) teaches quarterly taxes, deductions and worked examples across sixteen chapters.
What the math takes as given, and what it leaves out
The math trusts the profit figure you type. It does not work out your profit from sales and expenses, and it leaves out state tax, the QBI income limits and phase-outs, other deductions and credits, tax withheld from a job, and underpayment penalties. One scenario is all it runs. It is a headline check for one question: roughly how much federal tax does this profit owe, and what should each quarterly payment be.
Read more: quarterly taxes without the April surprise
The Kollaz Money guide Freelancer Quarterly Taxes 2026: Safe Harbor Rules walks through the same payment dates with the safe harbor rules that protect you from underpayment penalties when your income moves around.
Sources
- Self-employment tax rate 15.3 percent (12.4 percent Social Security plus 2.9 percent Medicare), the 2026 wage base of $184,500 on combined wages and net earnings, the extra 0.9 percent Medicare tax thresholds ($200,000 single, $250,000 married filing jointly), and the deduction for the employer-equivalent half of SE tax: IRS, Self-employment tax (Social Security and Medicare taxes), irs.gov, checked 2026-11-10. The wage base is also stated in IRS Tax Topic 751 for earnings in 2026.
- Net earnings factor of 92.35 percent of net profit, the four 2026 payment due dates (April 15, June 15, September 15, 2026 and January 15, 2027), four equal payments, and the rule that a due date on a Saturday, Sunday or legal holiday moves to the next business day: IRS Form 1040-ES (2026), Estimated Tax for Individuals, checked 2026-11-10.
- 2026 standard deductions ($16,100 single, $32,200 married filing jointly) and the 2026 federal income tax brackets (single bands starting at $12,400, $50,400, $105,700, $201,775, $256,225 and $640,600; joint bands at double the first two and $211,400, $403,550, $512,450 and $768,700): IRS Revenue Procedure 2025-32, announced in the IRS tax year 2026 inflation adjustments release, checked 2026-11-10.
- QBI deduction of up to 20 percent of qualified business income: IRS, Qualified business income deduction (Section 199A), irs.gov, checked 2026-11-10. This page applies the flat 20 percent to net profit as a disclosed simplification.
- Product names and prices are the Kollaz catalog entries KM-013, KM-027 and KM-017 (catalog.json, checked 2026-11-10). The verdict tiers on this page (effective rate at most 20 percent, at most 30 percent, above 30 percent) are a house display rule for this tool only, recorded in the build notes. They are not an IRS benchmark and not advice.
Educational information only, not tax or financial advice. Consider a qualified professional for decisions about your specific situation.