Car Loan Interest Deduction Calculator

An MCP server that calculates the 2025-2028 car loan interest deduction, the new SALT cap, the $2,200 child tax credit and the 2025 and 2026 federal brackets from the One Big Beautiful Bill Act (P.L. 119-21), using IRS forms and revenue procedures.

Hosted endpoint, no sign-in and no token:

https://car-loan-interest-deduction-calculator-mcp.lipmichal.workers.dev/mcp

Tools

Tool	What it does
calculate_car_loan_interest_deduction	Deduction for car loan interest after the $10,000 cap and the $200-per-$1,000 MAGI phase-out over $100,000 ($200,000 joint). Checks the vehicle and loan tests: new, US final assembly, personal use, loan after 2024, under 14,000 lb, first lien, not a lease.
calculate_salt_deduction	Deductible state and local tax under the $40,000 (2025) and $40,400 (2026) cap, the 30% phase-down over $500,000 / $505,000 MAGI and the $10,000 floor. Covers 2027-2029 steps and the 2030 return to $10,000. Optionally compares itemizing with the standard deduction.
get_tax_brackets_and_standard_deduction	2025 and 2026 brackets and standard deductions, the extra amount for age 65 or blind, and the tax and marginal rate on a given taxable income.
calculate_child_tax_credit	$2,200 per child and $500 per other dependent, the 5% phase-out, the tax liability limit and the refundable part up to $1,700 per child.

Every result has structured JSON, a plain-English summary, as_of, source (the irs.gov document) and more (a calculator page on taxbreakcalc.com).

What it knows that your model does not

• The car loan interest deduction started in tax year 2025, after most models were trained. You can take it without itemizing.
• Its phase-out is $200 for each $1,000 or part of $1,000 over the threshold. One dollar over $149,000 (single) wipes out the last $200. Schedule 1-A line 28 rounds up.
• Only new vehicles with final assembly in the US qualify, the loan must be originated after December 31, 2024, and leases never count.
• Married filing separately can claim it, with the same $100,000 threshold as single filers.
• The SALT cap is $40,000 for 2025 and $40,400 for 2026, not $10,000. Above $500,000 of MAGI it shrinks by 30 cents per dollar, but never below $10,000.
• The 2026 standard deduction is $16,100 single and $32,200 joint (Rev. Proc. 2025-32). The child tax credit is $2,200, with up to $1,700 refundable.
• The IRS has not published 2027 amounts yet (checked 2026-11-02). The tools say so instead of guessing.

Install

Claude.ai custom connector or ChatGPT developer mode

Add a custom connector and paste the URL. No token is needed.

https://car-loan-interest-deduction-calculator-mcp.lipmichal.workers.dev/mcp

Claude Code

claude mcp add --transport http car-loan-interest-deduction https://car-loan-interest-deduction-calculator-mcp.lipmichal.workers.dev/mcp

Or run it locally:

claude mcp add car-loan-interest-deduction -- npx -y github:theluckystrike/car-loan-interest-deduction-calculator-mcp

Claude Desktop

Add this to claude_desktop_config.json:

{
  "mcpServers": {
    "car-loan-interest-deduction": {
      "command": "npx",
      "args": ["-y", "github:theluckystrike/car-loan-interest-deduction-calculator-mcp"]
    }
  }
}

Cursor

Add this to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "car-loan-interest-deduction": {
      "url": "https://car-loan-interest-deduction-calculator-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

VS Code

Add this to .vscode/mcp.json:

{
  "servers": {
    "car-loan-interest-deduction": {
      "type": "http",
      "url": "https://car-loan-interest-deduction-calculator-mcp.lipmichal.workers.dev/mcp"
    }
  }
}

Node 20 or newer is needed for the local npx version.

Example prompts

• "I bought a new Ford F-150 in March 2026 and paid $3,200 in loan interest. I file single with MAGI of $110,000. What can I deduct?"
• "Does a used car or a leased car qualify for the no tax on car loan interest deduction?"
• "We file jointly, MAGI $550,000, and paid $48,000 in state income and property tax in 2026. How much SALT can we deduct, and should we itemize?"
• "What is the 2026 standard deduction and what is my federal tax on $60,000 of taxable income?"
• "We have two kids under 17 and MAGI of $410,500. What is our 2026 child tax credit?"

Data sources

All numbers come from documents fetched on 2026-11-02: the 2025 Schedule 1-A and Form 1040 instructions, IRS Notice 2025-57, the 2025 Schedule A instructions and 2026 draft Schedule A, IRC 164(b)(7), Rev. Proc. 2024-40, Rev. Proc. 2025-32 and the 2025 Schedule 8812 with its instructions. See DATA_SOURCES.md for each item and URL.

Limitations

• Results are estimates, not tax advice.
• Federal income tax only. State taxes on the same items are not covered.
• It does not look up a VIN. Check final assembly on the vehicle label or the NHTSA VIN decoder.
• 2027-2029 SALT amounts follow the statute's 101% rule; the IRS may round them when it prints the forms.
• The child tax credit tool does not model the Schedule 8812 alternative for three or more children based on social security and Medicare tax.
• Overtime, tips and the senior deduction are in a separate server: no-tax-on-overtime-mcp.

More

Calculators and guides for people: taxbreakcalc.com.

Part of the Zovo MCP collection: https://mcp.zovo.one

Development

npm install
npm run build
npm test

src/core.ts holds all the rules and has no I/O. src/stdio.ts is the local entry and src/worker.ts is the Cloudflare Worker entry. Both use the same tool registry in src/tools.ts.

License

MIT

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The paid back-office collection (invoices, VAT, PDFs, spreadsheets) is at https://mcp.zovo.one