B2B checkout fields

Polski 1.13.0 adds an optional set of B2B fields to the WooCommerce checkout: a “Buying as a company” toggle and NIP, REGON, and IBAN fields. The fields appear in the classic WooCommerce checkout (woocommerce_billing_fields filter), are saved to standard order meta, and are read by the KSeF module and the pro invoice module without further configuration.

”Buying as a company” toggle

Checkbox polski_buying_as_company placed at the top of the billing section. Unchecked by default - the NIP, REGON, and IBAN rows are hidden until the customer ticks it. The toggle state is saved to order meta _polski_buying_as_company (yes / no).

The show/hide logic is implemented as inline JavaScript - no build pipeline or extra frontend dependency. The script also listens for the jQuery updated_checkout event, so it works after asynchronous fragment refreshes of the checkout block.

NIP

billing_nip field validated against the Polish NIP checksum algorithm (10 digits, weights 6, 5, 7, 2, 3, 4, 5, 6, 7, modulo 11). Accepted input formats: 1234567890, 123-456-78-90, 123 456 78 90, and PL1234567890 (the prefix is stripped before validation). The value is stored in normalized form (10 digits) under the _billing_nip order meta.

Validation in PHP uses the new static utility Polski\Util\NipValidator:

use Polski\Util\NipValidator;

NipValidator::isValid('5260250274');           // true
NipValidator::isValid('PL 526-025-02-74');     // true
NipValidator::normalize('PL 526-025-02-74');   // '5260250274'
NipValidator::format('5260250274');            // '526-025-02-74'

When polski-pro’s Polski\Pro\Validation\NipValidator is active, FREE skips its own NIP registration to avoid a duplicate billing_nip field. REGON and IBAN are always added by FREE.

REGON

Optional billing_regon field (off by default). Accepts 9 or 14 digits (short / long REGON). Regex check: /^\d{9}$|^\d{14}$/. Saved to _billing_regon order meta.

IBAN

Optional billing_iban field (off by default). Structural sanity check: 2-letter country prefix + 2 check digits + 11-30 alphanumeric body characters, total length 15-34. Strict mod-97 verification is intentionally left to integrators (for example a payment gateway plugin). Saved to _billing_iban order meta.

Settings (polski_b2b)

Key	Default	Description
enabled	true	Master switch for the module
show_company_toggle	true	Whether to show the “Buying as a company” checkbox
nip	true	Whether to add the NIP field (skipped when polski-pro NipValidator is active)
regon	false	Whether to add the REGON field
iban	false	Whether to add the IBAN field

Enable REGON and IBAN via update_option:

update_option('polski_b2b', array_merge(
    (array) get_option('polski_b2b', []),
    ['regon' => true, 'iban' => true]
));

Integration with other modules

• KSeF module (FREE) reads _billing_nip from the order and automatically detects orders that require an e-invoice.
• Invoice module (PRO) reads _billing_nip as nipBuyer when generating Faktura VAT and correction invoices.
• AI Feed for invoices (PRO) exposes invoices as Markdown with NIP fields in the “Parties” block.

Admin display

NIP, REGON, and IBAN are added to the “Billing details” block on the order screen (woocommerce_admin_billing_fields). They are edited in the same place as the customer’s billing address.

Block checkout compatibility

Starting with Polski 1.14.0, NIP / REGON / IBAN are registered via the WooCommerce woocommerce_register_additional_checkout_field API (WC 8.6+). A single registration covers both the classic checkout and the Block checkout (Cart & Checkout Blocks). Validation runs on both sides.

The WC API stores values under _wc_billing/polski/nip, _wc_billing/polski/regon, _wc_billing/polski/iban order meta. Polski automatically mirrors them to the legacy keys _billing_nip, _billing_regon, _billing_iban (woocommerce_set_additional_field_value action) so the KSeF and pro invoice modules read the data with no changes.

Stores on WooCommerce older than 8.6 continue to use the classic-only registration path (woocommerce_billing_fields) with the “Buying as a company” toggle and inline JavaScript.