WooCommerce plugin hooks

Reference for version 1.2.3.

WooCommerce plugin

What a hook can change

For a country VIESAC already checks live (EU-27, Northern Ireland, Great Britain, Norway, Switzerland, Liechtenstein, Serbia, Turkey, Bosnia and Herzegovina, North Macedonia, Albania, Iceland, and Australia, including territories that fold into those countries), your code can run an extra step. VIESAC then runs its own registry check and, when the order qualifies, still creates the audit. A hook cannot mark that number valid, cannot skip the registry, and cannot skip the audit.

For a country VIESAC does not check live, a number that contains only letters and digits can remove tax as an export. VIESAC does not call a registry and does not create an audit. Your own check can refuse that exemption. An empty field, or a number that contains any other character, keeps the shop's tax and does not block checkout.

A hook can keep tax. It cannot grant 0% when the decision engine refused it. If any cart item refuses the exemption, the whole cart stays taxed.

Actions

Filters

Register the matching accepted argument count in add_filter. Existing argument positions are retained: the VAT field filter keeps checkout as its second argument; the company filter keeps billing/shipping there. In 1.2.3, viesac_is_vat_required receives the address country instead of an empty string and a context array instead of null.

Country-dependent field arguments and requirements apply to Classic Checkout and saved address forms. Classic fields update on WooCommerce's normal country-change refresh and preserve entered values. Saved address forms use their country when the form is built. Checkout Blocks use separate field registration and do not use these field-definition filters; shared cart exemption restrictions do apply to Blocks.

Examples

Change the existing VAT field by country. This applies to both billing and shipping; no extra VAT field is created. The optional fourth argument lets you restrict the change to one section.

add_filter('viesac_vat_field_args', function ($args, $context, $country, $section) {
    if ($country === 'BA') {
        $args['label'] = 'PDV number';
        $args['placeholder'] = 'BA201133590005';
    } elseif ($country === 'IS') {
        $args['label'] = 'VSK or kennitala';
        $args['placeholder'] = 'IS23148';
    }
    if ($country === 'US') {
        $args['type'] = 'hidden';
        $args['required'] = false;
    }
    // To change billing only: return $args early when $section !== 'billing'.
    return $args;
}, 10, 4);

Customize the company field for billing only. Omitting a section condition applies your rule to each section when its filter runs. An empty section is not an instruction to update both fields.

add_filter('viesac_company_field_args', function ($args, $section, $country) {
    if ($section === 'billing' && $country === 'AL') {
        $args['label'] = 'Registered business name';
    }
    return $args;
}, 10, 3);

Require VAT for billing addresses in a chosen country.

add_filter('viesac_is_vat_required', function ($required, $country, $context) {
    if ($country === 'EE' && $context['section'] === 'billing') {
        return true;
    }
    return $required;
}, 10, 3);

Keep tax for one product when the effective destination matches your rule. Physical orders use the active shipping destination; purely virtual orders use billing.

add_filter('viesac_cart_item_allows_exemption', function ($allowed, $product, $decision, $context) {
    if ($product instanceof WC_Product
        && $product->get_sku() === 'LOCAL-ONLY'
        && $context['supply_country'] === 'NO') {
        return false;
    }
    return $allowed;
}, 10, 4);

Keep tax for one product. The rest of the cart stays taxed as well.

add_filter('viesac_cart_item_allows_exemption', function ($allowed, $product) {
    if ($product instanceof WC_Product && $product->get_sku() === 'LOCAL-ONLY') {
        return false;
    }
    return $allowed;
}, 10, 2);

Refuse an export for a country VIESAC does not check. This does not create an audit.

add_filter('viesac_unverified_export_eligible', function ($eligible, $country, $number) {
    if ($country === 'EG' && strlen($number) < 9) {
        return false;
    }
    return $eligible;
}, 10, 3);

Print the stored note on a PDF invoice. The plugin does not call the PDF plugin itself.

add_action('wpo_wcpdf_after_order_data', function ($document_type, $order) {
    if (!$order instanceof WC_Order) {
        return;
    }
    $note = (string) $order->get_meta('_viesac_vat_exemption_note');
    if ($note !== '') {
        echo '<p>' . esc_html($note) . '</p>';
    }
}, 10, 2);

Checkout field labels can also use the existing viesac_checkout_field_text filter.