MCP server

Invaro Opentax Official

io.github.Invaro/opentax

Checked 25 Oct 2026, 20:29 UTC · Connected to it and listed its tools

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

At a glance

Type

MCP server

Publisher

invaro.ai (verified by the MCP Registry)

Status

Working at last check

Tools

15

Token cost

About 195,323 tokens per request

Sets up in

Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok

Last checked

25 Oct 2026, 20:29 UTC

Connect it to your agent

Add to CursorAdd to VS CodeVS Code Insiders

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

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

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

[mcp_servers.opentax]
url = "https://opentax.invaro.ai/mcp"

Gemini CLI

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

Cursor

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

VS Code

{"servers":{"opentax":{"type":"http","url":"https://opentax.invaro.ai/mcp"}}}

Antigravity

agy mcp add opentax https://opentax.invaro.ai/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"opentax","server_url":"https://opentax.invaro.ai/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"opentax","server_url":"https://opentax.invaro.ai/mcp"}

Tools

• calculate_business_tax ~4746 tokens
  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)/DRD/NOL, § 250, GBC/FTC/BEAT), S-corp entity taxes, corporate estimates, the § 4501 buyback excise, AET and PHC taxes. Individual returns →
• calculate_fiduciary_tax ~572 tokens
  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 exemption, after the §§ 651/661 distribution deduction. Retained capital gains refuse loudly (§ 1(h) trust breakpoints not modeled). Grantor tru
• calculate_tax ~61317 tokens
  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 — call this, and report ONLY numbers returned by oracle calls made with the real facts (never hand-check or approximate a line the oracle can
• compare_filing_statuses ~222 tokens
  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 their error instead of guessing.
• compute_return ~61197 tokens
  Compute the COMPLETE Form 1040 bottom-line set in one call — the 17 lines that determine the return (1a, 9, 10, 11, 12e, 15, 16, 17 AMT, 19, 22, 23, 24, 25d, 27a, 28, 32, 33, 34/37), each whole-dollar rounded by the engine. Takes the SAME input as calculate_tax (prefer the documents block: transcrib
• compute_state_return ~64298 tokens
  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 / MD 502 / MO-1040 / WI Form 1 / MN M1 / SC1040 / AL Form 40 / OR-40 / OK Form 511 / CT-1040 / KS K-40 / AR AR1000F / NM PIT-1 / NE 1040N /
• determine_dependent ~1217 tokens
  Determine whether ONE candidate person is the taxpayer's § 152 dependent — qualifying child or qualifying relative, including multiple-support agreements and the divorced-parents release — as a proof-backed yes/no with citations. Feed the result into calculate_tax's credits group (qualifyingChildren
• explain_rule ~232 tokens
  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 data), the rules and facts it depends on, and its content hash. Use to quote and explain the actual law behind an answer. Pass asOf to see o
• find_tax_cliffs ~304 tokens
  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, CTC phase-out steps. Every probe is a real evaluation.
• is_tipped_occupation ~157 tokens
  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-matches the job name; returns the official listing (name, TTC code, category) or a definitive 'not listed'.
• list_input_facts ~98 tokens
  Discover every input the tax corpus understands: id, type, whether required, and its documented default. Call this if unsure what information to collect from the user.
• lookup_tax_parameter ~181 tokens
  Look up the current-law dollar amounts behind a question ('standard deduction', 'CTC phase-out threshold', 'tips deduction cap') with their statutory citations and validity windows. Use this to fact-check ANY tax number before stating it — your training data likely predates the OBBBA.
• search_tax_rules ~236 tokens
  Full-text search over the encoded tax-law corpus ('kiddie tax', 'NIIT threshold', 'california renters credit'). Returns matching rules: id, title, statutory citation, effective window, and a verbatim excerpt of the law text. A hit means the engine computes this; zero hits means it is outside the cor
• verify_fact ~224 tokens
  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 / refuted (with the correct value and citation) / unknown. Never states a verdict it cannot ground.
• verify_tax_claim ~322 tokens
  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 self-check before presenting any tax number. Put asOf (and target, if any) INSIDE the facts object — e.g. facts: {..., "asOf": "2025-12-31"}

Browse

• GitHub tools
• Hiring and jobs
• Legal research
• GitHub and code hosting
• Speech to text

Related MCP servers

• Agent Arbitration
  Deterministic, machine-verifiable dispute resolution for A2A escrows.
• The Undesirables TCG Oracle
  TCG oracle: calibrated prices & risk, AI grading, loan terms, fantasy souls - proven on-chain. 23 to
• Vealth
  Vealth work board: find real work, claim free with your wallet, prove it. Free onchain anchoring.
• Redeal
  Neutral fairness computation for agents: fair division, verifiable random, Shapley shares.
• Kaiku
  Issue tracker and wiki for teams and their agents: find, file and update issues, write pages.
• emem, shared verifiable memory (MCP server)
  Verifiable memory for AI agents, checkable offline
• Agent Guild
  Rank agents; signed machine messages + wallet gates via x402; free verifiable agent passports.
• Insight Oracle
  Decision-input integrity for onchain AI agents: verify oracle prices before signing a trade.

Badge for your README

[![AptLynx](https://aptlynx.net/badge/io.github.Invaro/opentax.svg)](https://aptlynx.net/servers/io.github.Invaro/opentax)

Listing text is written by the maker; AptLynx lists tools and does not vouch for them. Find another tool · Browse by topic · For agents