io.github.Invaro/opentax

up checked 2026-11-11T07:38:50.902Z

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Publisher-provided description

Verifiable US tax oracle for AI agents: cited, machine-checkable federal and state tax computation

Summary by lookupd

Computes and verifies US federal and state tax figures for individuals, businesses, and trusts, citing the underlying statutory rules.

Install

Claude Code, remote (streamable-http)

claude mcp add --transport http opentax https://opentax.invaro.ai/mcp

Claude Code, npm package (stdio)

claude mcp add opentax -- npx -y @invaro/opentax

Codex, remote (streamable-http)

codex mcp add opentax --url https://opentax.invaro.ai/mcp

Codex, npm package (stdio)

codex mcp add opentax -- npx -y @invaro/opentax

Cursor, remote (streamable-http) → .cursor/mcp.json

{
  "mcpServers": {
    "opentax": {
      "url": "https://opentax.invaro.ai/mcp"
    }
  }
}

Cursor, npm package (stdio) → .cursor/mcp.json

{
  "mcpServers": {
    "opentax": {
      "command": "npx",
      "args": [
        "-y",
        "@invaro/opentax"
      ]
    }
  }
}

Other clients: docs. Or tell your agent: Set up lookupd for me: read https://lookupd.com/agent.md and follow it.

Tools (17 tools)

Publisher-provided text

• calculate_tax Compute US federal INDIVIDUAL income tax (or balance due if withholding is given) from a content-addressed corpus of cited rules. NEVER estimate tax yourself —
• calculate_business_tax Compute US federal BUSINESS-ENTITY tax from the same cited corpus: check-the-box entity classification, Form 1120 corporate income tax (§ 179/168(k)/174A/163(j)
• calculate_fiduciary_tax Compute US federal income tax for an ESTATE or TRUST (Form 1041): the § 1(e) compressed brackets and § 642(b) exemption. Input is taxable income before the exem
• determine_dependent Determine whether ONE candidate person is the taxpayer's § 152 dependent — qualifying child or qualifying relative, including multiple-support agreements and th
• compute_state_return Compose a STATE return's printed-form line set deterministically (2025 IL-1040 / VA 760 / CA 540 / NY IT-201 / PA-40 / NJ-1040 / OH IT 1040 / NC D-400 / GA 500
• compute_return Compute the COMPLETE Form 1040 bottom-line set in one call — the lines that determine the return (1a, 9, 10, 11, 12e, 15, 16, 17 AMT, 19, 20, 22, 23, 24, 25d, 2
• compute_form_2210 Form 2210 — the estimated tax underpayment penalty (26 U.S.C. § 6654) for tax years 2025-2027, composed from the printed form: Part I (the required annual payme
• compute_form_4562 Form 4562 — depreciation for an individual's businesses and rentals, tax years 2025-2027 (calendar year): § 179 expensing with the dollar limit, phase-out, marr
• verify_tax_claim Verify a claimed tax amount (yours, a user's, or another tool's) against the law. Returns verdict 'verified' or 'refuted' with the correct value. Use this as a
• list_input_facts Discover every input the tax corpus understands: id, type, whether required, and its documented default. Call this if unsure what information to collect from th
• explain_rule Get a tax rule in full: statutory citation with its verbatim excerpt, validity window, parameters, the formula and applicability guard (the rule IR — rules are
• find_tax_cliffs Find exact dollar amounts where one more cent of an input costs MORE than a cent of tax (marginal rate over 100%) — e.g. the EITC investment-income kill switch,
• compare_filing_statuses Compute the answer under every filing status for the same facts — e.g. to answer 'should we file jointly or separately?'. Statuses that need more facts report t
• lookup_tax_parameter Look up the current-law dollar amounts behind a question ('standard deduction', 'CTC phase-out threshold', 'tips deduction cap') with their statutory citations
• search_tax_rules Full-text search over the encoded tax-law corpus ('kiddie tax', 'NIIT threshold', 'california renters credit'). Returns matching rules: id, title, statutory cit
• verify_fact Fact-check a claimed dollar amount about tax law ('the 2026 MFJ standard deduction is $32,200', 'CTC is $2,000 per child') against the corpus. Returns verified
• is_tipped_occupation Determine whether a job is on the Treasury Tipped Occupation list (Treas. Reg. § 1.224-1, final Apr 2026) for the § 224 'no tax on tips' deduction. Fuzzy-matche

Details

• Version: 0.2.1
• Transports: streamable-http, stdio
• Uptime (7 days): 100%
• Median latency: 494 ms
• First indexed: 2026-11-01T09:10:43.986Z
• Last seen in registry: 2026-11-01T09:10:43.986Z

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