Gravity Forms VAT-ID Field

Adds a dedicated **European VAT ID (USt-IdNr.) field** to Gravity Forms with robust server-side
validation: a local format and per-country length check plus an optional online verification against
the **EU VIES** service or the **German BZSt eVatR** confirmation service. The VAT ID is also offered
as a reusable **Gravity Forms Settings API field** and the add-on ships a shared, extensible
**”e-Invoicing Fields”** settings page.

Features

**VAT ID form field** — drag-and-drop field in the form editor (group *e-Invoicing Fields*).
**Local validation** — structure check, EU country prefix and per-country length (incl. the VATspecials `EL` Greece and `XI` Northern Ireland).
**Optional country restriction** — accept only VAT IDs of one configured country.
**Online validation (per field, optional):**
**EU VIES** — validates any EU VAT ID via the official VIES REST API.
**German BZSt eVatR** — confirms a *foreign* EU VAT ID against your *own German* VAT ID.
**Never blocks on outages** — if the chosen online service is unavailable or inconclusive, the local check remains authoritative and the submission is not rejected.
**Shared “e-Invoicing Fields” settings page** — central place for the company’s own VAT ID; designed
to be extended by other add-ons through the `spgf_einvoice_fields_sections` filter.
**Reusable Settings API field** — a `vat_id` field type for the Gravity Forms Settings API that any
add-on can use in plugin/feed settings, with the same format validation.
**Normalized storage** — the VAT ID is stored upper-case and stripped of separators.
**Internationalized** — English and German translations included.
**Dependency-free** — both REST calls use the WordPress HTTP API; no Composer packages required.

Settings-Field Coding

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

See Plugin in Action

Read the Documentation