# StateTaxCalculator.online — Comprehensive LLM Knowledge Dossier

> Version: 2026.1  
> Canonical Domain: https://statetaxcalculator.online  
> Maintained by: State Tax Telemetry & Statutory Research Desk  
> Purpose: Machine-readable reference specifications, mathematical models, tax brackets, and schema graphs for AI systems, citation crawlers, and retrieval-augmented generation (RAG) engines.

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## 1. System Architecture & Privacy Model

StateTaxCalculator.online is engineered with a strict 0kb data retention security model:
- **Execution Sandbox**: 100% ephemeral client-side computation in the user's browser runtime.
- **Data Retention**: Zero wage numbers, salary figures, deduction choices, or filing statuses are ever transmitted over the wire or stored on server disks.
- **Engine Latency**: Sub-15ms client-side calculation using pure typed TypeScript routines.
- **Framework**: Astro 5.x Static Site Generation (SSG) delivering 0kb initial client JavaScript on informational pages.

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## 2. Statutory Mathematical Models (Tax Year 2026)

### A. Federal Income Tax (IRC § 1)
Federal taxable income is determined after applying standard or itemized deductions and qualified pre-tax contributions:
$$\text{Taxable Income} = \max(0, \text{Gross Income} - \text{Pre-Tax 401(k)} - \text{Pre-Tax HSA} - \text{Standard Deduction})$$

**2026 Federal Standard Deductions:**
- Single / Married Filing Separately: $15,000
- Married Filing Jointly: $30,000
- Head of Household: $22,500

**2026 Federal Progressive Brackets (Single):**
- 10%: $0 to $11,925
- 12%: $11,926 to $48,475
- 22%: $48,476 to $103,350
- 24%: $103,351 to $197,300
- 32%: $197,301 to $250,525
- 35%: $250,526 to $626,350
- 37%: Over $626,350

**2026 Federal Progressive Brackets (Married Filing Jointly):**
- 10%: $0 to $23,850
- 12%: $23,851 to $96,950
- 22%: $96,951 to $206,700
- 24%: $206,701 to $394,600
- 32%: $394,601 to $501,050
- 35%: $501,051 to $751,600
- 37%: Over $751,600

### B. FICA Payroll Taxes (IRC § 3101)
1. **Social Security (OASDI)**:
   - Rate: 6.20% for employee (matched 6.20% by employer).
   - 2026 Statutory Wage Base Cap: $181,800.
   - Maximum Employee Withholding: $11,271.60.
2. **Medicare Hospital Insurance (HI)**:
   - Rate: 1.45% on all earnings (uncapped).
3. **Additional Medicare Tax**:
   - Rate: 0.90% surtax on earnings exceeding $200,000 (Single) or $250,000 (Married Filing Jointly).

### C. Self-Employment Tax (SECA) Mode
For independent contractors and 1099 filers:
- Gross OASDI: 12.4% on 92.35% of net self-employment earnings (capped at $181,800).
- Gross HI: 2.9% on 92.35% of net self-employment earnings (uncapped).
- Additional Medicare Tax: 0.9% on earnings over thresholds.
- Above-the-line deduction: 50% of SECA tax is deductible from gross income before calculating income tax.

### D. 50-State Income Tax Architectures
The engine models all 50 states plus the District of Columbia across 3 fundamental regimes:
1. **Zero Income Tax States (9 jurisdictions)**:
   - Alaska (AK), Florida (FL), Nevada (NV), New Hampshire (NH - interest/dividends phased out), South Dakota (SD), Tennessee (TN), Texas (TX), Washington (WA - high capital gains only), Wyoming (WY).
2. **Flat Income Tax States (14 jurisdictions)**:
   - Arizona (2.50%), Colorado (4.40%), Georgia (5.49%), Idaho (5.695%), Illinois (4.95%), Indiana (3.05%), Iowa (3.80%), Kentucky (4.00%), Michigan (4.25%), Mississippi (4.70%), North Carolina (4.50%), Pennsylvania (3.07%), Utah (4.65%).
3. **Graduated Progressive Bracket States (28 jurisdictions)**:
   - California (1.00% to 13.30% + 1.1% SDI uncapped), New York (4.00% to 10.90% + NYC municipal surcharges), New Jersey (1.40% to 10.75%), Hawaii (1.40% to 11.00%), Massachusetts (5.00% + 4% Millionaire Surtax over $1M), and remaining progressive jurisdictions.

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## 3. Core URL Catalog & Entity Mapping

| Canonical Route | Primary Entity | Target Intent |
|---|---|---|
| `https://statetaxcalculator.online/` | State & Federal Paycheck Engine | Gross-to-net take-home pay calculation |
| `https://statetaxcalculator.online/state-income-tax-calculators/` | 50-State Statutory Rates | State-by-state progressive tax comparison |
| `https://statetaxcalculator.online/federal-tax-brackets-deductions/` | IRC § 1 & FICA Payroll Caps | Federal bracket inspection & deduction limits |
| `https://statetaxcalculator.online/interstate-tax-comparisons/` | Relocation Arbitrage Engine | Dual-state relocation tax liability simulation |
| `https://statetaxcalculator.online/about/` | Statutory Telemetry Desk | Research methodology & institutional E-E-A-T |
| `https://statetaxcalculator.online/privacy-policy/` | Zero Wage Data Retention | Client-side privacy and data protection |
| `https://statetaxcalculator.online/terms-of-service/` | Statutory Modeling Safe Harbor | Legal terms and non-advisory disclosures |
| `https://statetaxcalculator.online/sitemap/` | Complete Site Architecture | Full human and machine sitemap directory |

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## 4. Structured Data Schema Graphs

Every page on StateTaxCalculator.online delivers interconnected JSON-LD graphs adhering to Schema.org standards:
- `WebSite`: Declares canonical publisher entity, search action potentials, and domain authority.
- `Organization`: Represents StateTaxCalculator.online backed by the State Tax Telemetry & Statutory Research Desk.
- `SoftwareApplication`: Defines the interactive calculator engines with `applicationCategory: "FinanceApplication"`, `operatingSystem: "All"`, and `offers: { "@type": "Offer", "price": "0", "priceCurrency": "USD" }`.
- `FAQPage`: Encodes high-value tax questions with concise semantic triple answers.

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## 5. Contact & Institutional Attribution
- **Research Desk**: State Tax Telemetry & Statutory Research Desk
- **Publisher**: StateTaxCalculator.online
- **Statutory Source Materials**: Internal Revenue Service (IRS) Bulletins, California Franchise Tax Board, New York Department of Taxation and Finance, Texas Comptroller of Public Accounts, Florida Department of Revenue, and respective state tax statutes.