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AnswerLive data

Can Claude calculate the car loan interest deduction?

Only if it knows the 2025 law, and many Claude versions don't, or know it only in outline. The deduction runs from 2025 to 2028, is capped at $10,000 a year, phases out above $100,000 of MAGI ($200,000 joint) and only covers new vehicles with US final assembly bought on a loan made after 2024. Connect the free Car Loan Interest Deduction server and Claude checks each rule and works out the deduction and the phase-out.

Connect free, no token Car loan interest deduction MCP server

What Claude does alone, and what needs the server

Claude on its own

  • Explains in general terms that some car loan interest became deductible.
  • Adds numbers you give it.

With the Car Loan Interest Deduction server

  • The P.L. 119-21 rules: the cap, the MAGI phase-out and the vehicle tests.
  • A clear no when a used car, a lease or a business vehicle fails a test.
  • The 2025 and 2026 brackets, SALT cap and child tax credit for the rest of the return.

A real call to the live server

We sent this to the hosted server on 2026-11-03. The answer below is the server's own text, not a mock-up. Live values will differ when you ask.

You ask

I am single with $85,000 MAGI. I bought a new US-assembled car on a loan made in March 2025 and paid $2,400 interest in 2025. What can I deduct?

Tool call

calculate_car_loan_interest_deduction {"filing_status":"single","magi":85000,"tax_year":2025,"interest_paid":2400,"loan_origination_date":"2025-03-15","new_vehicle":true,"us_final_assembly":true,"personal_use":true}

Server answer

Interest counted $2,400, $2,400 after the $10,000 cap. MAGI $85,000 is not over the $100,000 threshold, so nothing is phased out. Car loan interest deduction for 2025: $2,400. Assumed: the gross vehicle weight rating is under 14,000 pounds; the loan is secured by a first lien on the vehicle; the vehicle is a car, minivan, van, SUV, pickup truck or motorcycle.

Connect it in 1 minute

One URL, no token, no account. In Claude.ai or Claude Desktop open Settings, then Connectors, then Add custom connector, and paste the URL.

Connector URL

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

Claude Code

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

Cursor (~/.cursor/mcp.json)

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

VS Code (.vscode/mcp.json)

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

All 4 tools, sources and more prompts: Car loan interest deduction MCP server · TaxBreakCalc

Questions

Can Claude calculate the car loan interest deduction?
Only if it knows the 2025 law, and many Claude versions don't, or know it only in outline. The deduction runs from 2025 to 2028, is capped at $10,000 a year, phases out above $100,000 of MAGI ($200,000 joint) and only covers new vehicles with US final assembly bought on a loan made after 2024. Connect the free Car Loan Interest Deduction server and Claude checks each rule and works out the deduction and the phase-out.
Do I have to itemize?
No. It is a deduction you can take with the standard deduction, on Schedule 1-A.
How do I check final assembly?
The vehicle label on the window shows it, or the NHTSA VIN decoder. The server asks for it as a yes or no.
Is the server free?
Yes. The Car Loan Interest Deduction server is free at its hosted URL with no token, key or account. The source is open on GitHub.

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