Quaderno MCP Server

Connect any AI assistant to Quaderno's tax compliance engine via the Model Context Protocol.
Calculate taxes. Validate tax IDs. Create invoices. All from natural language.

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The Problem

Tax compliance across borders is a nightmare. Different VAT rates per country, tax ID validation against government databases, reverse charge rules, digital services taxes... and your AI assistant can't help because it has no access to real-time tax data.

The Solution

This MCP server gives any AI assistant (Claude, GPT, etc.) direct access to Quaderno's tax engine. Ask in plain English, get accurate, compliant answers.

You: "What tax should I charge for a SaaS sale to a customer in Spain?"
AI:  IVA at 21% — status: taxable, currency: EUR

Tools

Tool	What it does
calculate_tax	Real-time tax rate calculation by country, postal code, and product type
validate_tax_id	Validate VAT/GST/ABN numbers against EU VIES, UK HMRC, and more
create_contact	Create customers and companies with full billing details
create_invoice	Generate tax-compliant invoices with automatic tax calculation
list_invoices	Search and filter invoices by contact, status, or date

Quick Start

1. Get your API key

Sign up at quaderno.io or create a free sandbox account for testing. Find your API key in Settings > API Keys.

2. Configure for Claude Desktop

Add to your config file:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "quaderno": {
      "command": "node",
      "args": ["/path/to/quaderno-mcp-server/dist/index.js"],
      "env": {
        "QUADERNO_API_KEY": "sk_live_your_key_here",
        "QUADERNO_API_URL": "https://your-account.quadernoapp.com/api"
      }
    }
  }
}

For sandbox testing, use https://your-account.sandbox-quadernoapp.com/api

Examples

Tax calculation

"What's the VAT rate for selling digital services in Spain?"

{
  "country": "ES",
  "name": "IVA",
  "rate": 21.0,
  "tax_code": "eservice",
  "status": "taxable",
  "currency": "EUR"
}

Tax ID validation

"Is this Spanish tax ID valid? ESB86412491"

{
  "valid": true
}

Full invoicing flow

"Create a company contact for TechCorp in Madrid and invoice them 500 EUR for consulting"

The AI will chain create_contact → create_invoice automatically, producing a tax-compliant invoice with the correct Spanish IVA applied.

Supported Tax Jurisdictions

Quaderno supports real-time tax calculation for 200+ countries and tax ID validation for:

• EU: All 27 member states (VAT via VIES)
• United Kingdom: VAT via HMRC
• Switzerland: UID
• Australia: ABN/GST
• New Zealand: GST
• Canada: Quebec QST

Development

git clone https://github.com/AnderRahe/quaderno-mcp-server.git
cd quaderno-mcp-server
npm install
cp .env.example .env   # Add your credentials
npm run build

Test with MCP Inspector

npx @modelcontextprotocol/inspector node ./dist/index.js

Environment Variables

Variable	Required	Description
QUADERNO_API_KEY	Yes	Your Quaderno private API key
QUADERNO_API_URL	Yes	Full API base URL including /api

Built With

• Model Context Protocol SDK — Server framework
• Quaderno API — Tax compliance engine
• Zod — Schema validation
• TypeScript + stdio transport

License

MIT