Australian tax API and MCP server for AI agents

Every calculation on this site is free to use from AI assistants and your own code: connect Claude, ChatGPT, Cursor or any MCP client to our MCP server, call the JSON API, or install the open-source JavaScript library. No sign-up or API key.

Why use it instead of the model's memory? Australian tax rates changed on 1 July 2026 (the 16% rate fell to 15%), and PAYG withholding uses the ATO's own formulas and rounding, not the tax brackets. AI models trained before then get these numbers wrong. These tools use the ATO's published formulas and match every row of the ATO's sample data for 2025–26 and 2026–27.

Connect an AI assistant (MCP)

Server URL (Streamable HTTP, no login):

https://aftertaxau.com/mcp

Claude and ChatGPT: add a custom connector and paste the URL above.

Claude Code:

claude mcp add --transport http au-tax https://aftertaxau.com/mcp

Cursor, Windsurf and other clients (mcp.json):

{
  "mcpServers": {
    "au-tax": {
      "url": "https://aftertaxau.com/mcp"
    }
  }
}

Run it locally instead (Node 18 or later, works offline):

{
  "mcpServers": {
    "au-tax": {
      "command": "npx",
      "args": [
        "-y",
        "au-compliance-kit",
        "mcp"
      ]
    }
  }
}

Tools

Tool	What it does
`take_home_pay`	Take-home pay in Australia for a salary or hourly rate: gross pay, PAYG tax withheld, net pay and employer super for each week, fortnight and month and for the year, plus the actual tax owed for the year and the likely refund.
`payg_withholding`	Exact amount an Australian employer must withhold from one pay under the ATO's PAYG withholding Schedule 1 (NAT 1004), for weekly, fortnightly, monthly or quarterly pays in 2025-26 or 2026-27.
`bonus_withholding`	PAYG tax to withhold from a bonus, commission or similar one-off payment made with a regular pay in Australia (ATO Schedule 5, Method A), for 2025-26 or 2026-27..
`annual_tax_estimate`	Income tax owed for an Australian financial year and the refund or bill against tax withheld: tax at resident or foreign rates, low income tax offset, seniors and pensioners tax offset, Medicare levy (including family and low-income reductions), Medicare levy surcharge, and compulsory HELP/study loan repayments.
`super_guarantee`	Australian superannuation guarantee (12%) an employer pays on earnings, or split a total package that includes super into salary and super..
`validate_au_identifier`	Check an Australian Business Number (ABN), Australian Company Number (ACN) or tax file number (TFN) with the official check-digit algorithms, or check the format of a BSB or bank account number.
`tax_rates`	Official Australian individual tax rates and thresholds for a financial year: resident and foreign resident brackets, low income tax offset, Medicare levy and surcharge thresholds, HELP repayment thresholds, seniors offset and the super guarantee rate.

JSON API

Every tool is also a plain web address, so an assistant that can only open links can still use it. Send the same fields as query parameters, or POST them as JSON. The OpenAPI description works with custom GPT actions and API clients.

https://aftertaxau.com/api/take_home_pay?salary=80000

{
  "taxYear": "2026-27",
  "perPay": {
    "fortnightly": {
      "grossPay": 3076.92,
      "taxWithheld": 622,
      "takeHomePay": 2454.92,
      "superGuarantee": 369.23
    }
  },
  "year": {
    "grossPay": 80000,
    "taxWithheld": 16172,
    "takeHomePay": 63828,
    "superGuarantee": 9600,
    "basis": "26 fortnightly pays"
  },
  "taxForTheYear": {
    "incomeTax": 14520,
    "lowIncomeTaxOffset": 0,
    "seniorsAndPensionersTaxOffset": 0,
    "medicareLevy": 1600,
    "medicareLevySurcharge": 0,
    "studyLoanRepayment": 0,
    "totalTax": 16120,
    "taxWithheld": 16172,
    "estimatedRefund": 52
  },
  "calculatorPage": "https://aftertaxau.com/salary/80000/"
}

curl -X POST https://aftertaxau.com/api/annual_tax_estimate \
  -H "Content-Type: application/json" \
  -d '{"salary": 95000, "deductions": 1800, "studyLoan": true}'

Other tools: /api/take_home_pay, /api/payg_withholding, /api/bonus_withholding, /api/annual_tax_estimate, /api/super_guarantee, /api/validate_au_identifier, /api/tax_rates. /api lists them with their fields.

JavaScript library

The same calculations as an npm package with no dependencies, for payroll and HR software:

npm install au-compliance-kit

import { calculateWithholding, estimateAnnualTax } from "au-compliance-kit";

calculateWithholding({ earnings: 2026.77, period: "fortnightly", payDate: "2026-11-13" });
// { withholding: 284, scale: 2, ... }

What's covered

PAYG withholding for 2025–26 and 2026–27: tax-free threshold, no TFN, foreign residents, HELP and study loans, Medicare levy exemptions and family variations, tax offsets, seniors and pensioners, and bonuses (Method A).
Income tax for 2025–26, 2026–27 and 2027–28 (an estimate), with offsets, the Medicare levy and surcharge, and study loan repayments.
Super guarantee (12%) and ABN, ACN, TFN, BSB and account number checks.

Not covered yet: working holiday makers, back payments, termination payments, and Fair Work award rates.

Fair use and privacy

The API and MCP server are free for reasonable use. We don't store the amounts you send. Results are general information, not tax advice, and we're not affiliated with the ATO.