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VAT Validation API for Accounting and Invoicing Tools

Accounting and invoicing software that handles EU B2B transactions can use the TaxID API to validate customer VAT numbers before generating zero-rated invoices. Prevent incorrectly zero-rated invoices and give users an auditable validation record.

Implementation steps

1. 1

   Validate when a user adds an EU customer

   When a user creates or updates a customer record with an EU VAT number, call GET /api/v1/validate/:country/:vat from your server. Display the returned company_name and company_address so the user can confirm they are adding the correct company.

2. 2

   Block zero-rate invoices for unvalidated customers

   Prevent your invoice UI from allowing zero-rate treatment until the customer's VAT number has been validated as 'active'. Show a validation badge on the customer record — green for active, yellow for pending re-validation, red for invalid.

3. 3

   Store the validation record on each invoice

   When generating a zero-rated invoice, attach the TaxID request_id, the validated company_name, company_address, and validation timestamp to the invoice record. This creates the audit trail required by EU invoice rules.

4. 4

   Re-validate reverse-charge customers on a schedule

   Run a monthly background job using the TaxID batch endpoint to re-validate all customers marked as reverse-charge. Notify accountants of any numbers that have become invalid so they can update customer records and adjust upcoming invoices.

Code example

const res = await fetch(
  'http://localhost:3000/api/v1/validate/DE/DE123456789',
  { headers: { 'Authorization': 'Bearer YOUR_API_KEY' } }
);
const { valid, status, company_name, company_address } = await res.json();

if (valid) {
  console.log(`Valid EU business: ${company_name}`);
} else if (status === 'service_unavailable') {
  // VIES is temporarily down — retry or allow with manual check
  console.log('VIES unavailable — check back in a few minutes');
} else {
  console.log('Invalid VAT number — charge local tax rate');
}

import requests

res = requests.get(
    "http://localhost:3000/api/v1/validate/DE/DE123456789",
    headers={"Authorization": "Bearer YOUR_API_KEY"}
)
data = res.json()

if data["valid"]:
    print(f"Valid: {data['company_name']}")
elif data["status"] == "service_unavailable":
    print("VIES temporarily unavailable")
else:
    print("Invalid VAT number")

API response

The TaxID API returns a consistent JSON response for every validation request:

{
  "valid": true,
  "status": "active",
  "country_code": "DE",
  "vat_number": "123456789",
  "company_name": "Example GmbH",
  "company_address": "Musterstraße 1, 10115 Berlin",
  "request_date": "2026-05-10T00:00:00.000Z",
  "cached": false,
  "request_id": "req_01j..."
}

Error handling

The API uses a consistent Stripe-style error format. Always handle service_unavailable separately — VIES has occasional downtime and you should not reject valid customers during outages.

Evaluating EU VAT APIs? Compare TaxID vs Vatstack, Vatlayer, Avalara →

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