GravityForms - VAT-ID Field

Gravity Forms VAT ID Field — Validate EU VAT IDs (VIES & German BZSt eVatR)

Collect and verify European VAT IDs (USt-IdNr.) in your Gravity Forms — with real, server-side validation, optional live online checks against EU VIES and the German BZSt eVatR service, and a reusable Settings API field for developers. No Composer, no external libraries, no monthly fees.

Whether you run B2B checkout forms, partner/reseller onboarding, e-invoicing intake, or any form that captures a VAT number, this add-on makes sure the value you store is actually a valid European VAT ID — not just a string that “looks right”.

Why you’ll love it

• ✅ Real validation, not just a regex. Structure, EU country prefix and per-country length are all checked on the server, where it can’t be bypassed.
• Optional live online verification against the official EU VIES REST API and the German BZSt eVatR confirmation service — turn it on per field.
• ️ Never loses a sale to an outage. If an online service is down, slow or inconclusive, the local check stays authoritative and the submission is not blocked.
• Developer-friendly. Ships a reusable vat_id Gravity Forms Settings API field and stores your own VAT ID in a standard add-on settings page (Forms → Settings → VAT ID Field).
• ⚡ Lightweight & dependency-free. Uses the built-in WordPress HTTP API — no Composer install, no bundled SDKs, no bloat.
• Translation-ready. English and German included, fully internationalized.

Key features

A dedicated VAT ID form field

• Drag-and-drop field in the form editor, grouped under e-Invoicing Fields.
• Clean single-line input, auto-normalized to upper-case and stored without separators (e.g. DE 123 456 789 → DE123456789).

Robust, layered validation (server-side)

1. Structure — two-letter country prefix followed by 2–13 alphanumeric characters.
2. EU country + length — the prefix must be a known EU VAT country, including the VAT specials EL (Greece) and XI (Northern Ireland), with the correct per-country length.
3. Optional online check (configurable per field):
   • EU VIES — validates any EU VAT ID against the official VIES service.
   • German BZSt eVatR — confirms a foreign EU VAT ID against your own German VAT ID (qualified “USt-IdNr.-Bestätigung”). Falls back to VIES automatically when eVatR doesn’t apply.

Robustness first: only a definitive invalid result ever blocks a submission. Timeouts, rate limits and service outages can never reject a legitimate customer.

Optional country restriction

Accept VAT IDs from one specific country only — perfect for region-specific forms.

Own VAT ID in the add-on settings

Your company’s own German VAT ID (used as the requester for the eVatR confirmation) is entered once under Forms → Settings → VAT ID Field — a standard Gravity Forms add-on settings page, right where you’d expect it.

Reusable Settings API field (vat_id)

Expose the same VAT ID validation inside any add-on’s plugin or feed settings:

 $fields[] = array(     'name'  => 'company_vat_id',     'type'  => 'vat_id',     'label' => __( 'Company VAT ID', 'your-textdomain' ),     'class' => 'medium', ); 

How online verification works

• Format / length only — no external call; pure local validation.
• EU VIES (ec.europa.eu) — validates any EU VAT ID.
• German BZSt eVatR (api.evatr.vies.bzst.de) — confirms a foreign EU VAT ID against your own German VAT ID.

The eVatR procedure requires your own German VAT ID (set once under Forms → Settings → VAT ID Field) and can only confirm VAT IDs from other member states; when it doesn’t apply, the add-on transparently falls back to VIES.

What’s included

• The plugin (form field + reusable vat_id Settings API field + shared settings page).
• English and German translations (.po / .mo / .pot).
• Full documentation in English and German (README + feature overview).
• Clean, heavily commented, object-oriented code — easy to read, extend and audit.

Requirements & compatibility

• WordPress with Gravity Forms ≥ 2.5
• PHP ≥ 7.4 (with the standard json extension)
• Works alongside the companion Gravity Forms SEPA Fields add-on (IBAN / BIC) — they share the same “e-Invoicing Fields” group and settings page without conflicts.

Privacy / GDPR

When an online check is enabled, the submitted VAT ID (and, for a qualified eVatR check, any company name/address passed) is transmitted to the selected external service — the EU Commission (VIES) and/or the German Federal Central Tax Office (BZSt eVatR). The add-on itself stores no data beyond the form entry value. Mention this in your site’s privacy policy where required.

Support & updates

Clean, well-documented code that’s easy to maintain. Localization-ready out of the box. Built to follow Gravity Forms’ official add-on framework and Settings API conventions, so it stays compatible as your stack evolves.

Changelog

1.2.0

• Reworked & extended online validation: per-field Validation method select (none / EU VIES / German BZSt eVatR), replacing the former “Validate against VIES” checkbox (legacy value still honored).
• New online validator wrapping the VIES and BZSt eVatR REST services (dependency-free).
• New shared, extensible “e-Invoicing Fields” settings page holding your own German VAT ID.
• VAT ID is now also a reusable Gravity Forms Settings API field (vat_id).
• Online services never block a submission when unavailable or inconclusive.

1.1.0

• Split off into a standalone plugin providing only the VAT ID field (per-country length / EU-prefix check, optional default-country restriction, optional VIES check).