How does the Validate Tax Number endpoint work?

Consejo

Last updated on 2025-09-10.

The Validate Tax Number endpoint in SIGN ES allows users to verify a NIF against the AEAT database or a VAT number against the VIES service.

We recommend using this endpoint to:

• Confirm that the recipient of an invoice is correct, helping prevent errors when the invoice is issued and transmitted to the tax authority.

• Validate data before creating a Taxpayer, ensuring the issuer’s details are correct prior to creating related resources.

 

NIF Validation (AEAT Service)

• The NIF validation endpoint only works in Production (LIVE), because the AEAT service does not provide a test environment.

• When calling this endpoint in TEST, the response will always be: INVALID

• For integration testing, you can use predefined tax numbers in TEST. Each number simulates a different outcome:

**       T00000001** → INVALID_SIMILAR

**       T00000002** → VALID

**       T00000003** → VALID_REMOVED

**       T00000004** → VALID_REVOKED

 

VAT Number Validation (VIES Service)

• The VAT number validation endpoint (for any EU country other than Spain) works in both TEST and Production (LIVE) environments.