Self-Employment Tax & Quarterly Estimated Tax Calculator
Estimate your 2026 self-employment tax, the half-SE-tax and QBI deductions, and a quarterly estimated tax payment based on your net self-employment profit.
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This calculator estimates your 2026 self-employment tax, the half-SE-tax and QBI deductions, and a quarterly estimated payment based on your net self-employment profit. This is the 15.3% combined Social Security and Medicare tax freelancers and independent contractors owe on top of federal income tax.
Total Federal Tax Owed
$17,147
Self-Employment Tax
$11,304
Est. Quarterly Payment
$4,287
Your Income
2026 Quarterly Due Dates
- April 15, 2026: Q1 2026 (Jan 1 – Mar 31 income)
- June 15, 2026: Q2 2026 (Apr 1 – May 31 income)
- September 15, 2026: Q3 2026 (Jun 1 – Aug 31 income)
- January 15, 2027: Q4 2026 (Sep 1 – Dec 31 income)
Tax Breakdown
| Net SE earnings (92.35% of profit) | $73,880 |
| Social Security portion (12.4%, up to $184,500 wage base) | $9,161 |
| Medicare portion (2.9%, no cap) | $2,143 |
| Self-employment tax | $11,304 |
| Additional Medicare Tax (0.9% over $200,000) | $0 |
| Half-SE-tax deduction (above the line) | $5,652 |
| QBI deduction (20%, simplified) | $12,650 |
| Taxable income | $50,599 |
| Federal income tax | $5,844 |
| Total federal tax (income tax + SE tax) | $17,147 |
| Estimated quarterly payment | $4,287 |
How Self-Employment Tax Works
Self-employment tax is the 15.3% combined Social Security and Medicare tax that independent contractors, freelancers, and sole proprietors owe in place of the FICA tax an employer would otherwise split with an employee. See IRS: Self-Employment Tax (Social Security and Medicare Taxes) and Form 1040-ES (2026) for quarterly payment rules.
The Formula
Half of SE tax is deductible above the line; QBI adds a separate 20% deduction.
A Worked Example
Take this calculator's defaults: $80,000 in net self-employment profit, no W-2 wages elsewhere, $5,000 of other income, filing single. Net SE earnings are 92.35% of profit ($73,880), well under the $184,500 Social Security wage base, so the full amount owes 12.4% for Social Security ($9,161) plus 2.9% for Medicare ($2,143), for $11,304 of self-employment tax. Half of that, $5,652, is deductible above the line. The 20% QBI deduction on qualified business income of $74,348 (profit minus the half-SE-tax deduction) would be $14,870, but it's capped at 20% of taxable income before the QBI deduction ($63,248), so $12,650 is allowed. Taxable income comes out to $50,599, for $5,844 of federal income tax. Add the $11,304 self-employment tax and the total federal tax bill is $17,147, about $4,287 per quarter across four estimated payments.
Who This Applies To
- Sole proprietors, freelancers, and independent contractors with net self-employment profit of $400 or more.
- Partners in a partnership who materially participate on their share of partnership income.
- Anyone expecting to owe $1,000 or more in tax for the year beyond withholding generally needs to make quarterly estimated payments.
What This Doesn't Cover
- The QBI deduction is simplified to a flat 20% rate. It doesn't model the phase-in range for specified service trades/businesses or W-2 wage/UBIA limits at higher income.
- It doesn't account for self-employed health insurance or retirement plan contributions, which can further reduce taxable income.
- It doesn't calculate an exact underpayment penalty, only the safe-harbor percentages to aim for.
This is an estimate for planning, not a substitute for professional advice. A CPA or enrolled agent can run your exact numbers, including any state-level self-employment or franchise tax.
Common Questions
?Why is only 92.35% of my profit taxed for SE tax?
It's a long-standing feature of the SE tax formula (IRC Sec. 1402(a)), meant to roughly mirror how an employer's share of FICA tax isn't itself counted as employee wages. It applies before the 15.3% combined rate, not after.
?What if I also have a W-2 job?
Your W-2 wages count first against the Social Security wage base ($184,500 for 2026). If your W-2 wages already meet or exceed that, none of your self-employment earnings owe the 12.4% Social Security portion. Only the 2.9% Medicare portion applies, which has no cap.
?Do I actually have to make quarterly payments?
Generally yes, if you'll owe $1,000 or more in tax for the year and your withholding won't cover it. The IRS instructions and due dates are on Form 1040-ES.
?What counts toward the safe harbor to avoid a penalty?
Paying in, through withholding and estimated payments combined, at least 90% of this year's tax or 100% of last year's tax (110% if last year's AGI was over $150,000) generally avoids the underpayment penalty.
?Is the QBI deduction modeled exactly here?
No. This calculator uses a simplified flat 20% QBI calculation. It doesn't model the phase-in range for specified service trades/businesses or the W-2 wage/UBIA of qualified property limits that apply at higher income. A tax professional can run the exact Form 8995/8995-A calculation for your situation.
About this calculator. Results are estimates for education and planning, based on the inputs you enter and the published formula described above. Everything runs in your browser; nothing you type is sent to us or stored. It is not financial, tax, legal or medical advice. Read the disclaimer and our methodology.
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