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Tax ID Verification for KYC (Know Your Customer) Workflows

KYC for B2B onboarding requires verifying that counterparty businesses are legitimately registered. Use the TaxID API to validate VAT and Tax ID numbers as part of your KYC workflow, with real-time registry lookup and structured audit records.

Implementation steps

1. 1

   Collect the Tax ID at onboarding

   Add a VAT/Tax ID field to your B2B signup or onboarding form. Label it clearly for each market: 'VAT Number' for EU/UK, 'ABN' for Australia, 'MVA Number' for Norway. Use the country selected in the billing address to determine which label and format to display.

2. 2

   Validate in real time via the TaxID API

   On form submission, call GET /api/v1/validate/:country/:vat from your server. Return a loading state while the API call is in progress (VIES calls can take up to 2 seconds). Confirm the returned company_name matches the declared company name before proceeding — a mismatch is a KYC risk signal.

3. 3

   Cross-reference company name and address

   Compare the company_name and address from the API response against the customer's self-declared details. Use fuzzy matching to handle abbreviations and legal suffix variations (Ltd/Limited, GmbH, SRL). A substantial name mismatch should trigger a manual review step, not automatic rejection — the business may have recently rebranded or be filing under a trading name.

4. 4

   Store the KYC record at the account level

   Persist the full API response — vat_number, company_name, address, status, request_id, validated_at — with the customer account record. This is your KYC documentation showing that identity was verified at onboarding. The request_id ties back to the specific VIES query made at that point in time.

5. 5

   Schedule periodic re-validation for active accounts

   For accounts with elevated risk or regulatory exposure, schedule quarterly re-validation of all VAT numbers. For standard accounts, annual re-validation is typically sufficient. Automate this with the TaxID batch endpoint to process your full customer list in a single API call.

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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