POST Validation Operational

EU VAT & Global Tax ID Validator

Validates tax IDs across EU VAT (VIES), UK VAT, US EIN, Australian ABN, and Indian GSTIN. Returns business name, address, and registration status.

POST /api/validate-tax-id

Why Use This API?

Instantly validate tax identification numbers across multiple global jurisdictions. Verify business legitimacy, retrieve official registration details, and ensure tax compliance for B2B transactions. Supports real-time VIES lookups for EU VAT numbers with automatic fallback during service outages.

Code Examples

                curl -X POST https://api.atomicapis.dev/api/validate-tax-id \
  -H "X-RapidAPI-Proxy-Secret: YOUR_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "taxId": "DE123456789",
    "countryHint": "DE"
  }'
              

                const response = await fetch('https://api.atomicapis.dev/api/validate-tax-id', {
  method: 'POST',
  headers: {
    'X-RapidAPI-Proxy-Secret': 'YOUR_SECRET',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    taxId: 'DE123456789',
    countryHint: 'DE'
  })
});

const data = await response.json();
console.log(data);
              

                import requests

response = requests.post(
    'https://api.atomicapis.dev/api/validate-tax-id',
    headers={
        'X-RapidAPI-Proxy-Secret': 'YOUR_SECRET',
        'Content-Type': 'application/json'
    },
    json={
        'taxId': 'DE123456789',
        'countryHint': 'DE'
    }
)

data = response.json()
print(data)
              

                using System.Net.Http.Json;

var client = new HttpClient();
client.DefaultRequestHeaders.Add("X-RapidAPI-Proxy-Secret", "YOUR_SECRET");

var request = new
{
    taxId = "DE123456789",
    countryHint = "DE"
};

var response = await client.PostAsJsonAsync(
    "https://api.atomicapis.dev/api/validate-tax-id",
    request
);

var data = await response.Content.ReadFromJsonAsync<object>();
Console.WriteLine(data);
              

Description

The EU VAT & Global Tax ID Validator API provides comprehensive validation of tax identification numbers across multiple jurisdictions worldwide. Whether you're verifying EU VAT numbers through the official VIES (VAT Information Exchange System), checking US Employer Identification Numbers (EIN), or validating Australian Business Numbers (ABN), this API delivers accurate, real-time results.

Key Features

Real-time VIES Integration — Direct connection to EU's VAT Information Exchange System for live validation of EU VAT numbers
Multi-Jurisdiction Support — Validate tax IDs from EU, UK, US, Australia, and India with a single API
Business Details Retrieval — Get official business name, registered address, and current registration status
Automatic Fallback — Format validation continues to work even when government services are unavailable
Checksum Validation — Algorithmic checksum verification for UK VAT (mod 97), Australian ABN (mod 89), US EIN (IRS campus prefix), and Indian GSTIN (Luhn mod 36)

Supported Tax ID Formats

🇪🇺 EU VAT Numbers

All 27 EU member states via VIES

DE123456789, FRXX123456789

🇬🇧 UK VAT Numbers

Post-Brexit UK VAT validation

GB123456789, GB123456789001

🇺🇸 US EIN

Employer Identification Number

12-3456789, 98-7654321

🇦🇺 Australian ABN

Australian Business Number

12 345 678 901

🇮🇳 Indian GSTIN

Goods and Services Tax Identification Number

22AAAAA0000A1Z5

Request Parameters

Parameter	Type	Required	Description	Example
`taxId`	string	Yes	The tax identification number to validate	`DE123456789`
`countryHint`	string	Optional	ISO 3166-1 alpha-2 country code. Auto-detected if not provided.	`DE`

Tip: The countryHint parameter is optional because the API can often auto-detect the country from the tax ID format. However, providing it explicitly improves accuracy and response time.

Response Format

Example Response (200 OK)

{
  "isValid": true,
  "taxIdType": "eu_vat",
  "country": "DE",
  "formattedId": "DE123456789",
  "businessName": null,
  "businessAddress": null,
  "isActive": null,
  "validationMethod": "vies_fallback_format",
  "error": "VIES service unavailable. Format validation only."
}

Response Fields

Field	Type	Description
`isValid`	boolean	Whether the tax ID is valid
`taxIdType`	string	Type of tax ID: `eu_vat`, `uk_vat`, `us_ein`, `au_abn`, or `in_gstin`
`country`	string	ISO 3166-1 alpha-2 country code (e.g., `DE`, `GB`, `US`, `AU`, `IN`)
`formattedId`	string	The tax ID formatted according to its jurisdiction's standard format
`businessName`	string \| null	Official registered business name (if available)
`businessAddress`	string \| null	Registered business address (if available)
`isActive`	boolean \| null	Whether the registration is currently active (if available)
`validationMethod`	string \| null	Method used for validation: `vies_live`, `vies_fallback_format`, `checksum`, or `format_only`
`error`	string \| null	Error message if validation failed, otherwise null

Use Cases

B2B Invoice Validation

Automatically validate customer VAT numbers before issuing invoices to ensure tax compliance and avoid rejected claims.

                  // Validate before invoice
{
  "taxId": customer.vatNumber,
  "countryHint": customer.country
}
// Only issue 0% VAT invoice if valid
                

Tax Compliance

Maintain accurate tax records by verifying supplier and customer tax IDs for audit trails and regulatory compliance.

                  // Store validation record
{
  "validationMethod": "vies_live",
  "isActive": true,
  "isValid": true
}
                

Vendor Onboarding

Verify new vendors and suppliers during onboarding to ensure legitimate business entities and accurate tax documentation.

                  // Onboarding validation
if (response.isValid &&
    response.isActive === true) {
  approveVendor(vendor);
}
                

Build Constraints

Understanding the technical implementation details helps you design robust integrations. Here are the key architectural considerations for this API:

VIES SOAP API Integration

EU VAT validation connects directly to the official VIES (VAT Information Exchange System) SOAP API. This provides real-time validation but means response times may vary based on VIES availability (typically 500ms-2s).

Jurisdiction-Specific APIs

Non-EU validations (UK VAT, US EIN, ABN, GSTIN) use local checksum algorithms and format validation. UK VAT uses modulus 97, US EIN validates IRS campus prefixes, Australian ABN uses modulus 89, and Indian GSTIN uses Luhn mod 36. These validations are synchronous and very fast.

Format-Only Fallback

During VIES outages or when government services are unavailable, the API automatically falls back to format validation only. The response will include "validationMethod": "vies_fallback_format" or "format_only" to indicate this mode. Always check this field for critical validations.

Rate Limiting

VIES imposes rate limits on requests. The API has a 5-second HTTP timeout for VIES lookups and falls back to format-only validation if the service is unavailable. For high-volume use cases, consider implementing client-side caching with a TTL of at least 24 hours.

Data Freshness

VIES data is updated by member states on varying schedules. Some countries update in real-time, others batch update daily or weekly.

Error Codes

HTTP Status	Response Body	Description	Resolution
200	`{ "isValid": false, "error": "..." }`	Tax ID is invalid or unrecognized. The `error` field contains the reason (e.g., invalid format, failed checksum, unknown type).	Check the `error` field for details and correct the tax ID
400	`{ "message": "The 'taxId' field is required and cannot be empty." }`	The `taxId` field is missing or empty	Provide a non-empty `taxId` in the request body
400	`{ "message": "An error occurred during tax ID validation." }`	An unexpected error occurred during validation	Retry the request or contact support
401	`{ "message": "Unauthorized: Invalid or missing X-RapidAPI-Proxy-Secret header." }`	The API secret header is missing or invalid	Verify your `X-RapidAPI-Proxy-Secret` header value

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Ready to validate tax IDs?

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MCP Integration MCP Ready

What is MCP?

Model Context Protocol (MCP) allows AI assistants like Claude to call this API as a native tool during conversation. Instead of writing HTTP requests, the AI invokes the tool directly — no API keys or boilerplate needed on the client side.

Tool Details

Tool Class

TaxIdValidatorTools

Method

ValidateTaxId()

Description

Validates VAT and Tax IDs with optional VIES lookup