TaxStackHub Calculators

Free Tax Calculators for
U.S. Business Owners

18 free tools covering self-employment tax, entity structure savings, QBI deductions, quarterly payments, home office deductions, and 50-state tax comparisons. All updated for 2026 tax law, including the OBBBA QBI increase to 23%.

✓ 18 free calculators
✓ 2026 tax law current
✓ IRS-cited formulas
✓ No signup required
✓ Mobile-friendly

Foundation

Core Tax Calculators

Start here — these are the most-used tools.

🧮
PopularFree
SE Tax Calculator
Self-employment tax (Social Security + Medicare), income tax estimate, effective rate, and quarterly payment schedule for 2026.
15.3% SE tax · Up to $184,500 wage base
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PopularFree
Entity Comparison
LLC vs S-Corp vs C-Corp — 5-year tax projection showing which structure saves the most at your profit level.
Includes salary vs. distribution analysis
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PopularFree
S-Corp Election Generator
AI generates IRS Form 2553 and 5-year savings projection. See your $8K–$40K+ annual S-Corp savings before you elect.
Includes Form 2553 · AI-powered
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Free
QBI Deduction Calculator
Qualified Business Income deduction for 2026. OBBBA raised the rate from 20% to 23% and made it permanent. See your exact deduction.
23% QBI rate under OBBBA · Phase-out included
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Free
Quarterly Tax Estimator
Calculate quarterly estimated tax payments (Form 1040-ES) for QBI, SE tax, and income tax. Includes all 4 due dates.
Apr 15 · Jun 15 · Sep 15 · Jan 15

Freelancers & 1099 Workers

Freelancer Tax Tools

Everything a 1099 worker or sole proprietor needs.

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PopularFree
1099 Freelancer Tax Calculator
Full tax breakdown for 1099 contractors: SE tax, income tax, deductions, effective rate, and quarterly payment due dates.
Net profit → exact tax owed
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Free
Home Office Deduction
Simplified method ($5/sq ft, up to 300 sq ft) or regular method. Calculates your deduction based on home size and business use.
Up to $1,500/year simplified
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Free
Underpayment Penalty Calculator
Calculate IRS underpayment penalties (Form 2210) if you didn't make sufficient quarterly payments. See what the IRS charges and how to reduce it.
Based on Form 2210 Safe Harbor rules

S-Corp & Compensation

Entity & Salary Tools

For business owners who have elected or are considering S-Corp status.

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Free
S-Corp Salary Distribution
Determine the right W-2 salary for your S-Corp based on your duties, industry standards, and business type. Includes reasonableness documentation.
Market-rate salary analysis
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Free
Reasonable Salary Calculator
Check if your S-Corp salary meets IRS reasonable compensation standards (Durand factors). Prevents reclassification risk.
IRS Rev. Rul. 74-44 compliant

State & Advanced

State & Advanced Tools

Multi-state planning and deeper optimization.

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Free
50-State Tax Stack
Compare income tax, self-employment tax, and corporate tax across all 50 states. Find the most tax-efficient state for your business.
Corporate, income & SE tax for all 50 states
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Free
Expense Policy Generator
Generate a written business expense reimbursement policy — IRS-compliant documentation to support deductions if you're audited.
IRS audit-ready documentation

Reports & Pro

Optimization Reports

AI-powered reports that synthesize multiple calculations into an actionable plan.

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Free
Tax Optimization Report
Full tax optimization analysis: entity structure, QBI deduction, SE tax savings, quarterly payments, and an IRS-ready deduction checklist.
Multi-tool synthesis · deduction checklist
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Pro — $19
Entity Report with AI Chat
5-year LLC vs. S-Corp vs. C-Corp projection with real tax math, state tax checklist, PDF download, and AI tax expert chat.
5-year projection · PDF export · AI chat