# VAT Tax Validator MCP > VAT Tax Validator checks if a tax ID is valid for B2B invoicing globally. This MCP Server runs strict, local mathematical algorithms against European and international VAT/Tax numbers. It stops your agent from generating illegal invoices or drafting fraudulent contracts by proving the number's structure and checksum instantly. ## Overview - **Category:** finance-accounting - **Price:** Free - **Tags:** vat-validation, tax-compliance, checksum, b2b-invoicing, european-tax, data-verification ## Description The `validate_vat` tool checks a tax number string against country-specific algorithms, confirming whether a VAT or Tax ID format and checksum are mathematically correct. When you need to process B2B invoices or draft contracts, relying on simple pattern matching won't cut it; this server runs strict, local mathematical validation. You should know that LLMs often hallucinate these checks, which is risky when your agent uses the data for legal documents or invoicing. This MCP stops that problem dead in its tracks by running validations against native V8 math functions—it gives you certainty. When you feed this server a tax number and specify the country, the `validate_vat` tool doesn't just look at the letters; it runs an offline checksum check using algorithms specific to that region's tax structure. Your agent gets a clean result telling you if the ID is mathematically sound—no guesswork involved. If you're dealing with European commerce, this server handles EU VAT numbers. It checks both the required format and the mathematical checksum across every single country in the Union. This means your agent can confidently generate invoices knowing those VAT numbers are valid for cross-border payments. For global operations, the tool validates tax identification formats that go way beyond the EU scope. You're talking about supporting a wider array of international corporate identifiers. It handles structures from various jurisdictions so you don't have to build separate validation logic for every corner of the globe. The whole point is enforcing B2B compliance. Before your agent executes a payment action or finalizes an invoice, you can ensure that every tax ID used is structurally sound. If it fails the check—if its checksum is off or its format is wrong—your workflow stops immediately, preventing you from generating illegal invoices or drafting fraudulent agreements. This mechanism allows your AI client to treat tax validation like a hard mathematical truth, not just a text pattern. It's about proving the number works, period. ## Tools ### validate_vat Checks a given tax number string against country-specific algorithms to confirm if the VAT or Tax ID format and checksum are correct. ## Prompt Examples **Prompt:** ``` Validate the UK VAT number `GB123456789` before creating the invoice. ``` **Response:** ``` VAT Result: {"valid": false, "country": "United Kingdom"} ``` **Prompt:** ``` Check if this German tax ID is structurally valid: `DE123456788`. ``` **Response:** ``` VAT Result: Mathematical checksum validated successfully. ``` **Prompt:** ``` Verify the Italian VAT number provided by the supplier. ``` **Response:** ``` Validation complete: The IT VAT number format is invalid. ``` ## Capabilities ### Validate European VAT Numbers Checks the format and checksum of Value Added Tax numbers across all EU countries. ### Check International Tax IDs Validates tax identification formats beyond the EU, supporting a wider range of global corporate identifiers. ### Enforce B2B Compliance Ensures that any tax ID used by your agent for invoicing or contracts is structurally sound before proceeding with a payment action. ## Use Cases ### Drafting a Cross-Border Invoice A billing agent is creating an invoice for a supplier in Germany. Instead of proceeding, the agent first calls `validate_vat` with the German tax ID. The tool returns 'valid,' and the agent can safely proceed to create the record in Stripe. ### Cleaning Up Supplier Data The compliance team pulls a spreadsheet of 500 international supplier IDs. They pipe this list through `validate_vat` using a script, which immediately flags all non-compliant records for human review before onboarding. ### Contract Drafting Check A legal agent is generating an agreement that requires tax ID proof. The agent first uses `validate_vat` on the client's provided numbers. If it fails, the agent stops drafting and asks for a corrected number, preventing contract failure. ### Automated Data Import When importing records from an external ERP system into your database, the data pipeline runs `validate_vat` on every tax field. Only mathematically valid IDs are accepted, keeping your core data clean and compliant. ## Benefits - Avoid generating illegal invoices. By running `validate_vat`, your agent verifies the checksum of every European VAT number before calling an invoicing system like Stripe or Xero. - Cut compliance risk instantly. You don't have to trust general AI pattern matching; this tool uses strict, local mathematical algorithms to confirm tax ID validity. - Process diverse global data types. The validator handles both standard EU VAT IDs and other international corporate Tax IDs in one call. - Build reliable workflows. Your agent can check a list of 100 supplier IDs against `validate_vat` and only proceed with the batch if compliance is met. - Save time on audits. Instead of manually cross-referencing country tax rules, you pass data through `validate_vat` for an instant pass/fail report. ## How It Works The bottom line is you get a reliable pass/fail answer based on mathematics, not fuzzy logic or pattern matching. 1. Feed the MCP Server the tax number and required country code (if applicable). 2. Your AI client calls the `validate_vat` tool, which executes the necessary country-specific mathematical validation. 3. The server returns a structured result indicating whether the ID passed the checksum test. ## Frequently Asked Questions **Does VAT Tax Validator support all European countries?** Yes, it validates VAT numbers across all major EU countries using native V8 algorithms. It also supports certain international tax ID formats beyond the standard EU scope. **What happens if I pass an invalid number to `validate_vat`?** The tool returns a structured JSON result, explicitly marking 'valid' as false and providing details about why the checksum failed. Your agent can read this error directly. **Can I use `validate_vat` for US tax IDs?** While its core strength is EU VAT, the tool supports validating various international corporate Tax ID structures beyond just European standards. **Is using `validate_vat` faster than checking manually?** Absolutely. It runs algorithmic checks in milliseconds, eliminating the need for human intervention or complex multi-step API calls to multiple regional databases. **How does `validate_vat` perform its algorithmic checks?** It uses country-specific mathematical modulus algorithms. These aren't just format checks; they verify the number's internal consistency, which is required for proper B2B compliance. **What types of tax identifiers can `validate_vat` process?** The tool validates both standard European VAT numbers and general international corporate Tax IDs. It handles various regional standards beyond just the EU format. **What input format should I use when calling `validate_vat`?** You must pass the tax number as a raw string to the function. Your agent or client framework handles the necessary data type processing for validation. **How do I interpret the output JSON from `validate_vat`?** The resulting JSON object provides explicit boolean and country context. You can use fields like 'valid' and 'country' to programmatically determine if an invoice can proceed. **Does it connect to VIES API?** No, it checks the mathematical format (checksum) local. This guarantees sub-millisecond validation without network dependency. **Which countries are supported?** All European Union member states (GB, DE, FR, IT, ES, etc). **Does it validate corporate names?** No, it purely validates the mathematical format of the VAT number itself.