The Opentax MCP server,
connected in one click.
Verifiable US tax oracle for AI agents: cited, machine-checkable federal and state tax computation. Connect the official Opentax MCP server to Claude, ChatGPT, or Cursor through gate — one gateway URL, no config files, security-checked.
Free to start · No credit card · No hosting needed
What your AI can do with Opentax
Real prompts you can type the moment it's connected — no setup, no docs to read.
“Use “calculate_tax”: Compute US federal INDIVIDUAL income tax (or balance due if withholding is given) from a content-addressed corpus of cited rules. NEVER esti.”
“Use “calculate_business_tax”: Compute US federal BUSINESS-ENTITY tax from the same cited corpus: check-the-box entity classification, Form 1120 corporate income tax (§ 17.”
“Use “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 in.”
“Use “determine_dependent”: Determine whether ONE candidate person is the taxpayer's § 152 dependent — qualifying child or qualifying relative, including multiple-suppo.”
How secure is the Opentax MCP server?
Every server in the gate directory has to pass the same four checks before your AI can touch it. Here's how Opentax holds up.
Official endpoint
Operated by Opentax (invaro.ai) at its documented MCP endpoint — not a third-party mirror or community re-host.
No sign-in needed
This server only exposes public data — no account and no credentials are involved when you connect.
Scanned before it goes live
gate checks every tool for prompt injection, hidden instructions, data-exfiltration hints, and over-broad permissions before the server is available through your gateway.
Watched for drift
If Opentax adds or changes tools later, gate re-scans and alerts you — before your AI acts on the change.
Connected in three steps
Connect your gate
Add one gateway URL to Claude, ChatGPT, or any MCP client. One-time setup, about two minutes.
Pick Opentax
Choose Opentax in the gate directory. No sign-in needed.
Use it anywhere
Opentax's tools are live in every AI client you've connected — with rules and logging built in.
Free to start · No credit card · No hosting needed
The actual tools Opentax exposes
Fetched live from the official endpoint and re-checked daily by gate — not marketing copy.
calculate_tax — Compute US federal INDIVIDUAL income tax (or balance due if withholding is given) from a content-addressed corpus of cited rules. NEVER esti
calculate_business_tax — Compute US federal BUSINESS-ENTITY tax from the same cited corpus: check-the-box entity classification, Form 1120 corporate income tax (§ 17
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 in
determine_dependent — Determine whether ONE candidate person is the taxpayer's § 152 dependent — qualifying child or qualifying relative, including multiple-suppo
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
compute_return — 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,
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 v
list_input_facts — Discover every input the tax corpus understands: id, type, whether required, and its documented default. Call this if unsure what informatio
+ 7 more tools once connected
The Opentax MCP server at a glance
https://opentax.invaro.ai/mcpQuestions, answered
Is there an official Opentax MCP server?
Yes — Opentax operates its own remote MCP server at opentax.invaro.ai. gate connects you to that official endpoint and adds security scanning, per-tool access rules, and an activity log on top.
How do I connect Opentax to Claude or ChatGPT?
Add gate's gateway URL to your AI client once, then pick Opentax in the directory. No account or sign-in is needed. From then on, Opentax's tools are available in every client you've connected to gate.
Do I need to host anything?
No. Opentax runs the server, and gate is fully managed. You just connect one URL — there's nothing to install, deploy, or maintain.
Is the Opentax MCP server safe to connect?
It's the vendor's official endpoint, and gate scans its tools for prompt injection and hidden instructions before it goes live, re-checks it whenever it changes, and lets you allow, block, or require approval for every single tool.
Is it free?
Yes — you can get started with gate for free and connect Opentax in minutes. No credit card required.
Connect more than just Opentax
Every server below works through the same gateway URL — connect once, add tools anytime.
Squarespace DomainsDesignView →Set up Opentax in: Claude · Claude Code · ChatGPT · Cursor · VS Code