calcuris-mcp

npm version license

An MCP (Model Context Protocol) server that exposes the tax engines behind Calcuris — real 2026 US income tax & paycheck math, US state property tax, Canadian federal + provincial income tax, Australian income tax & stamp duty, and UK dividend tax. No API key, no network calls: every number is computed locally from data sourced from the IRS, Tax Foundation, CRA/Revenu Québec, the ATO and state revenue offices, and HMRC.

Quick Start

Run directly with npx — no install required.

Claude Desktop / Claude Code

Add to your MCP config (claude_desktop_config.json or .mcp.json):

config.json

{
  "mcpServers": {
    "calcuris": {
      "command": "npx",
      "args": ["-y", "calcuris-mcp"]
    }
  }
}

Cursor

Add to .cursor/mcp.json:

config.json

{
  "mcpServers": {
    "calcuris": {
      "command": "npx",
      "args": ["-y", "calcuris-mcp"]
    }
  }
}

Tools

Every response includes a source note and a reference_url pointing to the live calculator on calcuris.com that uses the same engine.

Tool	Description	Example call	Example response (excerpt)
`us_income_tax`	US federal (2026 IRS brackets, post-OBBBA) + estimated state income tax, with a full progressive bracket breakdown.	`{ "grossIncome": 95000, "filingStatus": "single", "stateCode": "CA" }`	`{ "federalTax": 12070, "stateTax": 4758.42, "totalTax": 16828.42, "marginalRate": 0.22, "takeHome": 78171.58 }`
`us_paycheck`	US take-home pay per pay period: federal withholding, Social Security, Medicare (+ Additional Medicare), state tax, net pay.	`{ "payType": "salary", "annualSalary": 80000, "payFrequency": "biweekly", "filingStatus": "single", "stateCode": "TX" }`	`{ "net": { "annual": 65110, "perPeriod": 2504.23 }, "federal": { "annual": 8770 }, "socialSecurity": { "annual": 4960 } }`
`us_property_tax`	Annual/monthly property tax from a home value and either a custom rate or a state's real 2026 effective rate.	`{ "homeValue": 450000, "stateCode": "TX" }`	`{ "annualTax": 6300, "monthlyTax": 525, "effectiveRatePct": 1.4 }`
`ca_income_tax`	Canadian federal + provincial/territorial income tax, CPP/QPP (+ CPP2/QPP2), EI/QPIP, and net take-home pay. Optional `compareAllProvinces`.	`{ "grossIncome": 75000, "provinceCode": "ON", "rrspContribution": 0 }`	`{ "federalTax": 8468.74, "provincialTax": 3696.06, "netIncome": 57465.69 }`
`au_income_tax`	Australian resident income tax (2025-26 ATO brackets) + Medicare levy, Medicare Levy Surcharge, LITO offset, HELP/HECS repayment.	`{ "taxableIncome": 95000, "privateHospitalCover": true, "hasHelpDebt": false }`	`{ "incomeTax": 19288, "medicareLevy": 1900, "totalTax": 21188, "takeHome": 73812 }`
`au_stamp_duty`	Australian state/territory stamp duty, including first-home-buyer concessions and the foreign purchaser surcharge. Optional `compareAllStates`.	`{ "propertyValue": 750000, "stateCode": "NSW", "firstHomeBuyer": false, "foreignResident": false, "principalResidence": true }`	`{ "baseDuty": 28162.5, "totalDuty": 28162.5, "effectiveRate": 3.755 }`
`uk_dividend_tax`	UK dividend tax with HMRC's stacking method (dividends sit on top of other income), tapered Personal Allowance, £500 dividend allowance, year-over-year comparison.	`{ "otherIncome": 40000, "dividends": 15000, "year": "2026/27" }`	`{ "dividendTax": 2741.25, "totalTax": 8227.25, "extraVsPrior": 290 }`

Each tool's inputSchema documents every field (types, enums, defaults) and is discoverable via tools/list — see the source in src/index.ts for the full parameter set.

Data sources & freshness

All engines target tax year 2026 (UK: 2026/27, with 2025/26 comparison built in). Rates and brackets are sourced from:

US — IRS Rev. Proc. 2025-32 (federal brackets, standard deduction, Child Tax Credit), SSA/IRS FICA wage base and rates, Tax Foundation (state income tax brackets and property tax effective rates), state revenue offices.
Canada — CRA (federal brackets, BPA, CPP/CPP2), Revenu Québec (QPP, QPIP, Quebec abatement), provincial finance ministries.
Australia — ATO (2025-26 individual tax rates, Medicare levy, LITO, HELP/HECS repayment thresholds), state and territory revenue offices (stamp duty schedules and first-home-buyer concessions).
UK — HMRC (Personal Allowance, dividend allowance, Income Tax bands and dividend rates for 2025/26 and 2026/27).

These are the same datasets that power the live calculators:

Disclaimer

Results are estimates for guidance only and do not constitute tax, legal, or financial advice. Tax situations vary by individual (local taxes, deductions, credits, and edge cases are not exhaustively modeled). Always confirm figures with a qualified tax professional or the relevant government authority before making financial decisions.

Development

Terminal

npm install
npm run build   # compiles src/ → dist/ with tsc
npm test        # spawns the built server and runs the smoke test

Calcuris README