Irs Taxpayer

🏛️ irs-taxpayer-mcp

Exact US tax numbers for year-end decisions, without sending your finances to a chatbot.

Deterministic TY2024 to TY2026 estimates · local no-model CLI · 45 MCP tools

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Estimates for planning and education only. Not tax, legal, or financial advice, and not filing software. See the legal notice.

Know the number before December 31

Should you convert $30,000 to Roth this year? Harvest gains in the 0% bracket? Top up your 401(k)? These decisions have deadlines, and a chatbot guess is not good enough when real money is on the line.

irs-taxpayer-mcp is a deterministic US individual tax engine for TY2024 through TY2026. It does the math from IRS annual tables, shows its work, and refuses to guess when a case is not supported.

• 🔒 Your numbers can stay on your machine. The direct CLI calculates locally, starts no MCP connection, calls no model, and sends no tax data anywhere.
• 🎯 Deterministic, not generated. The same inputs always give the same answer. A language model never does the arithmetic.
• 🛑 Fails closed. Unsupported states, years, or missing required facts return an error instead of a rough estimate.
• 🤖 Works with your AI assistant too. 45 MCP tools for Claude, Kiro, Cursor, and other MCP clients.

🚀 Try it in 30 seconds

npm install --global irs-taxpayer-mcp

irs-taxpayer-mcp intake --output taxpayer-facts.json # guided local questionnaire irs-taxpayer-mcp plan --facts taxpayer-facts.json

Example result for a synthetic TY2026 household (married filing jointly, $185,000 W-2, $12,000 long-term gains, two children):

# Local Tax Plan for TY2026

Adjusted gross income: $197,000 Taxable income: $164,800 Federal tax after refundable credits: $20,440 Employee FICA: $14,122 Total modeled tax: $34,562 Take-home income: $162,438

Privacy

Calculated directly by the local deterministic engine. No model, network request, persistence, or telemetry was used.

Add --json for structured output with assumptions, official sources, a calculation trace, and privacy.modelInvoked: false.

💡 Decisions it helps with

🔒 Privacy Architecture

⚡ Getting Started

Option A: Direct local mode (recommended for taxpayer facts)

Install once, before entering any tax facts:

npm install --global irs-taxpayer-mcp

Run the guided local questionnaire. It does not start MCP or invoke a model:

irs-taxpayer-mcp intake --output taxpayer-facts.json

Or create and edit a strict local template:

irs-taxpayer-mcp template --output taxpayer-facts.json

irs-taxpayer-mcp validate --facts taxpayer-facts.json

Calculate directly through the deterministic engine:

irs-taxpayer-mcp plan --facts taxpayer-facts.json

irs-taxpayer-mcp plan --facts taxpayer-facts.json --json

New facts files are created with mode 0600 on POSIX. On Windows, the CLI rejects existing symbolic links but relies on the current user's filesystem permissions. Existing files are not replaced unless --force is explicit. Imported JSON is limited to 1 MiB, rejects symbolic links and unknown fields, and does not accept names, SSNs, addresses, employer IDs, or account numbers.

Using npx may download the public package before execution, but the direct commands do not send the facts file or its values over the network.

Option B: MCP mode for AI assistants

The MCP server makes no network requests and stores no taxpayer data. However, facts typed into an MCP client may be processed by that client's model provider. Use direct local mode or a local-model MCP client when end-to-end local handling is required.

MCP Step 1: Add to your AI assistant

Add this to your MCP client configuration:

Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json):

{

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

Kiro (.kiro/settings/mcp.json):

{

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

Cursor: same format in Cursor's MCP settings.

MCP Step 2: Restart your AI assistant

After saving the config, restart the app. The MCP server will auto-download and connect.

MCP Step 3: Ask supported tax questions

The client model converts natural language into tool arguments. Do not enter real taxpayer facts here unless the selected MCP host and model satisfy your privacy requirements:

• _"Calculate my federal tax: $150k income, married filing jointly, 2 kids"_
• _"Compare California vs Texas vs Washington for $200k income"_
• _"I'm a freelancer making $80k: what are my quarterly estimated taxes?"_
• _"What tax credits am I eligible for? AGI $60k, single, one child"_
• _"Should I itemize or take the standard deduction? I pay $15k in mortgage interest and $12k in state taxes"_
• _"Explain the Backdoor Roth IRA strategy"_
• _"How much is the EITC for a family of 4 earning $35k?"_
• _"I exercised ISOs this year: will I owe AMT?"_
• _"Help me plan my year-end tax moves. I have a 401k and HSA."_

Alternative: Docker

docker build -t irs-taxpayer-mcp .

docker run -i irs-taxpayer-mcp

Alternative: Streamable HTTP Transport

npx irs-taxpayer-mcp --http --port 3000

MCP endpoint: http://127.0.0.1:3000/mcp

Health check: http://127.0.0.1:3000/health

HTTP mode is stateless and binds only to a loopback host by default. Browser requests must use an exact allowed Origin. Add a trusted browser Origin with a repeatable flag:

npx irs-taxpayer-mcp --http \

--allowed-origin https://trusted-client.example

The legacy --sse flag remains a deprecated alias for --http. The old /sse and /messages endpoints are not exposed.

🛠️ Tools (45)

All tools use the current MCP registerTool API. Each advertises read-only annotations and an output schema, and returns both human-readable text and structuredContent. Error results include a stable error code, message, and recovery suggestion.

The 1.0 flagship generate_tax_plan workflow returns domain structured results, assumptions, official source provenance, a calculation trace, and explicit unsupported boundaries. The deterministic engine performs no network requests, persistence, or telemetry. Its structured privacy metadata reports whether the MCP adapter or direct CLI path was used. Unsupported tax years, state profiles, and required worksheet facts fail closed. See Local Tax Planner 1.0 Contract.

Federal Tax Calculations

Deduction Analysis

Tax Credits

Retirement & Strategy

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