FinToku
US Business Federal Income Tax Calculator
Sole prop · Partnership · S-Corp · C-Corp · QBI · Self-employment tax
Estimate only — not tax advice. This tool simplifies a genuinely complex area of federal tax law (QBI wage/property limits, entity-level elections, multi-owner allocations, AMT, and state-specific franchise/margin taxes are not fully modeled). Figures reflect IRS Rev. Proc. 2025-32 and the One Big Beautiful Bill Act (OBBBA, signed July 4, 2025). Always confirm with a CPA/EA and irs.gov/businesses before filing.
Business entity type
Tax year
Owner's filing status
Used to apply individual brackets to pass-through income
$
Revenue minus ordinary operating expenses, before any owner compensation
Quick scenarios
Advanced options
Section 179 / bonus depreciation
Equipment/software expensed immediately
SEP-IRA / Solo 401(k) contribution
Reduces taxable income (not available to C-corps here)
Other deductions
Home office, health insurance, accountable-plan reimbursements, etc.
State
Approximate top personal rate used as a proxy — actual state corporate/franchise tax rules differ; verify with your state's department of revenue
What's simplified here: the QBI (Section 199A) wage/UBIA test above the phase-in range isn't fully modeled — we assume the deduction phases toward $0 above the top of the range unless you have significant W-2 wages/property, which is conservative. Multi-owner partnership/S-corp allocations, AMT, NIIT, and state franchise taxes aren't included either.
Total Business Tax
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Eff. rate —%
Net Profit After Tax
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— / mo
Federal Income / Corp Tax
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—
SE/Payroll + State Tax
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—
Net profit after tax
Federal tax
SE / payroll tax
State tax
Total tax at this profit level, by entity structure (same $ profit, same filing status/state)
Entity choice changes who pays SE/payroll tax and whether QBI applies — it doesn't change your actual business economics. Switching entities has real-world costs (payroll setup, filings); model it here, then confirm with a CPA.
Estimated quarterly payments — avoids an IRS underpayment penalty
| Quarter | Due date | Amount |
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Based on 1/4 of this year's estimated total tax. The safe-harbor rule (100% of last year's tax, or 110% if last year's AGI exceeded $150,000) can differ — check Form 1040-ES (pass-through) or Form 1120-W (C-corp).
Disclaimer. This calculator produces simplified, unofficial estimates for general planning purposes only — it is not tax, legal, or financial advice, and no advisor-client relationship is created by using it. It does not model AMT, NIIT, multi-owner allocations, the full QBI wage/UBIA limitation, state franchise/margin taxes, credits, or your complete personal tax situation. Figures reflect IRS Rev. Proc. 2025-32 and the One Big Beautiful Bill Act (OBBBA, signed July 4, 2025) as currently understood and may change. Always verify results with a licensed CPA/EA and irs.gov/businesses before filing or making tax payments.
Estimates only — not tax advice. Consult a CPA/EA before filing. FinToku