Free AI Tax Assistant — Connect ChatGPT, Claude & Gemini

If you sell online, you’ve probably typed a tax question into ChatGPT, Claude, or Gemini at some point — “do I need to register for VAT in Germany?” or “what’s the sales tax threshold in Texas?” The problem is that general-purpose AI chatbots aren’t tax specialists. They guess. They mix up old rules with new ones. They confidently give you the wrong number.

GoodVat fixes that. We built a free AI tax assistant connector, using a technology called MCP (Model Context Protocol), that plugs our entire tax encyclopedia — VAT, GST, and US sales tax rules for over 80 countries and states — straight into the AI assistant you already use. No new app to learn, no new login. You just keep chatting with ChatGPT, Claude, or Gemini like normal, except now it actually knows tax law.

This page explains what that means in plain English, and walks you through connecting it in a few minutes — even if you’ve never written a line of code.

The short version

Copy this address: https://api.goodvat.com/mcp. Paste it into your AI assistant’s “Connectors,” “Integrations,” or “MCP Servers” settings. Ask it a tax question. That’s it — skip to How to connect your AI assistant for exact steps per app.

What is MCP, in plain English?

MCP (Model Context Protocol) is an open standard, created by Anthropic (the company behind Claude), that lets AI assistants safely connect to outside tools and live data — instead of relying only on what they memorized during training.

Think of it like a USB cable for AI. Your laptop doesn’t natively know how to talk to a printer, a webcam, or a keyboard — it needs a cable and a driver. MCP is that cable for AI assistants. It lets ChatGPT, Claude, Gemini, and other AI tools “plug in” to outside services — like GoodVat — and pull real, up-to-date information instead of making an educated guess.

This is exactly why GoodVat built an MCP server: so any AI assistant that supports the standard can become an instant AI tax expert for VAT, GST, and US sales tax, sourced from guides our team writes and keeps updated, not from a model’s training data that might be a year out of date.

What you get once you connect

• Accurate tax Q&A — ask natural questions like “What’s the VAT rate in France for digital goods?” or “Do I owe sales tax in California this year?” and get sourced answers covering UK VAT, all 27 EU member states, all 50 US states + DC + Puerto Rico, India GST, and more.
• Live EU VAT number verification — your AI assistant can check any EU VAT number in real time against the official VIES registry, right inside your conversation.
• Always current — GoodVat’s guides are reviewed and updated regularly, so your AI assistant isn’t stuck quoting outdated thresholds or rates.
• No extra cost — the GoodVat MCP server itself is completely free. You only need an AI assistant that supports MCP connections (most modern AI chat apps do, or are adding it).

How to connect your AI assistant to GoodVat

There are two ways to connect, and which one you need depends on the app:

1. Remote connection (easiest) — most AI apps can connect straight to our hosted server over the internet. You just paste in an address. No installation.
2. Local bridge (for developer tools) — some AI coding tools only support local connections. For those, we publish a tiny free helper package, @goodvat/mcp-server, that bridges the two.

For almost everyone, you want option 1. The address you need is:

https://api.goodvat.com/mcp

Connect Claude (Claude.ai / Claude Desktop)

1. Open Claude and go to Settings.
2. Look for Connectors (sometimes called Integrations or Custom Connectors).
3. Choose to add a custom or remote connector and paste in https://api.goodvat.com/mcp as the URL.
4. Save, then start a new chat and ask Claude a tax question — for example, “Using GoodVat, what’s the OSS threshold for EU sellers?”

Connect ChatGPT

1. Open ChatGPT and go to Settings → Connectors (this is sometimes under an “Advanced” or “Developer” section, and availability can depend on your plan).
2. Add a new connector and enter https://api.goodvat.com/mcp as the server address.
3. Once it’s added, you can reference it in chat and ask your tax question directly.

If you don’t see a connectors option, ChatGPT’s MCP support is still rolling out across plans — check chatgpt.com for the latest availability on your plan.

Connect Gemini

Google is rolling out MCP support across the Gemini app and Gemini Enterprise. If your version of Gemini offers a “Connectors,” “Extensions,” or “Tools” option, add https://api.goodvat.com/mcp as a remote MCP server the same way as above. Developers using the Gemini CLI can add it directly to their MCP server configuration.

Connect Cursor, Windsurf, VS Code, Claude Code, and other dev tools

If you’re a developer (or work with one), add this to your MCP configuration file:

{
  "mcpServers": {
    "goodvat": {
      "url": "https://api.goodvat.com/mcp"
    }
  }
}

If your tool only supports local stdio servers instead of remote URLs, use the free bridge package instead:

{
  "mcpServers": {
    "goodvat": {
      "command": "npx",
      "args": ["@goodvat/mcp-server"]
    }
  }
}

This runs @goodvat/mcp-server (requires Node.js 18+), which simply forwards everything to the same hosted endpoint above — same data, same answers, just bridged for tools that need a local connection.

Where else you can find it

GoodVat’s MCP server is fully open — you’re welcome to inspect it, fork it, or just read how it works:

GitHub RepositoryFull source code, setup instructions, and the latest updates.

npm Package@goodvat/mcp-server — the free stdio bridge for local tools.

Listed on mcp.soFind GoodVat in the mcp.so directory of MCP servers.

Why use an AI tax assistant instead of just searching?

Searching the web for “do I need to register for VAT” gets you ten different blog posts written at ten different times, for ten different countries, half of them outdated. An AI tax assistant powered by GoodVat gives you one direct answer, sourced from guides that are actively maintained, and it can follow up — asking it “what about if I also sell to Germany?” works the way a real conversation should.

It’s especially useful if you’re running a small e-commerce business on Shopify, WooCommerce, Etsy, or TikTok Shop and don’t have an in-house tax team. You get expert-level answers about UK VAT, EU VAT and OSS, and US sales tax nexus on demand, in whatever AI chat app you already have open.

Not a replacement for an accountant

GoodVat’s MCP server gives you fast, sourced answers so you understand your obligations — but tax situations get complicated fast. For anything with real money on the line, confirm with a qualified accountant or tax advisor.

Frequently Asked Questions

What is the GoodVat MCP server? A free connector that lets AI assistants like ChatGPT, Claude, and Gemini access GoodVat’s tax knowledge directly, so you get sourced answers instead of guesses.

What does MCP stand for? Model Context Protocol — an open standard from Anthropic that lets AI assistants connect to outside tools and data, similar to how a USB cable connects a laptop to a printer.

Is it free? Yes, completely free. No account, API key, or subscription needed.

Can I connect ChatGPT, Claude, and Gemini at the same time? Yes — you can connect the same GoodVat MCP server to as many AI assistants as you like. Each one connects independently using the same address.

Does this replace my accountant? No. It’s a fast way to get accurate background information, not personalized tax advice.

See also

• GoodVat Tools Overview — all our free compliance tools
• EU VAT Number Checker — the same live VIES lookup, available as a standalone web tool
• US Economic Nexus Calculator — check your US sales tax obligations by state
• GoodVat Guides — the full plain-English tax reference this AI assistant draws from
• Model Context Protocol official site — the open standard behind this connector