For Developers

This section is intended for developers who want to integrate the module with custom solutions or invoicing plugins.

Order Meta Data

Business Details

Meta key	Description	Example
`_billing_ic`	Company ID (identification number)	`12345678`
`_billing_dic`	Tax ID (tax identification number)	`CZ12345678`
`_billing_dic_dph`	VAT ID (Slovakia only)	`SK1234567890`

VAT Exemption

Meta key	Description	Values
`is_vat_exempt`	WooCommerce standard - VAT exemption	`yes` / `no`
`_wpify_vat_exempt_reason`	Exemption reason	`domestic`, `export`, `reverse_charge`, `legacy`, `standard`

Example of Getting Data from Order

$order = wc_get_order( $order_id );

// Business details
$ic = $order->get_meta( '_billing_ic' );
$dic = $order->get_meta( '_billing_dic' );
$dic_dph = $order->get_meta( '_billing_dic_dph' );

// VAT exemption - use WooCommerce method
$is_vat_exempt = wc_string_to_bool( $order->get_meta( 'is_vat_exempt' ) );
$vat_exempt_reason = $order->get_meta( '_wpify_vat_exempt_reason' );

Customer Meta Data

Meta key	Description
`billing_ic`	Customer Company ID
`billing_dic`	Customer Tax ID
`billing_dic_dph`	Customer VAT ID (SK)

Getting Data from Customer

// Recommended way - using WC_Customer object
$customer = WC()->customer;

// VAT exemption - primary source is customer
$is_vat_exempt = $customer->get_is_vat_exempt();

// Business details
$ic = $customer->get_meta( 'billing_ic' );
$dic = $customer->get_meta( 'billing_dic' );

// Alternatively from user meta
$user_id = get_current_user_id();
$ic = get_user_meta( $user_id, 'billing_ic', true );
$dic = get_user_meta( $user_id, 'billing_dic', true );

Available Filters

`wpify_woo_icdic_eu_country_codes`

Modifies the list of EU countries for Reverse Charge calculation.

apply_filters( 'wpify_woo_icdic_eu_country_codes', $eu_countries );

Parameter	Type	Description
`$eu_countries`	array	Array of EU country codes (e.g., `['CZ', 'SK', 'DE', ...]`)

Return value: array - Modified array of country codes

Example:

/**
 * Modify EU countries list
 *
 * @param array $countries Array of EU country codes
 *
 * @return array Modified country array
 */
function my_modify_eu_countries( array $countries ): array {
    // Add country (e.g., after EU accession)
    $countries[] = 'XX';

    // Remove country
    $countries = array_diff( $countries, array( 'GB' ) );

    return $countries;
}
add_filter( 'wpify_woo_icdic_eu_country_codes', 'my_modify_eu_countries' );

`wpify_woo_icdic_vat_id_valid_for_exempt`

Custom Tax ID validation for VAT exemption. Allows VIES bypass or custom verification.

apply_filters( 'wpify_woo_icdic_vat_id_valid_for_exempt', $is_valid, $vat_id );

Parameter	Type	Description
`$is_valid`	bool	Validation result (from VIES or basic check)
`$vat_id`	string	Tax ID to validate (including country prefix, e.g., `CZ12345678`)

Return value: bool - Whether Tax ID is valid for exemption

Example:

/**
 * Custom Tax ID whitelist
 *
 * @param bool   $is_valid Validation result
 * @param string $vat_id   Tax ID to validate
 *
 * @return bool Modified result
 */
function my_vat_id_whitelist( bool $is_valid, string $vat_id ): bool {
    // Custom Tax ID whitelist - always valid
    $whitelist = array( 'CZ12345678', 'SK1234567890' );

    if ( in_array( $vat_id, $whitelist, true ) ) {
        return true;
    }

    return $is_valid;
}
add_filter( 'wpify_woo_icdic_vat_id_valid_for_exempt', 'my_vat_id_whitelist', 10, 2 );

`wpify_woo_icdic_destination_country`

Overrides destination country used for VAT calculation.

apply_filters( 'wpify_woo_icdic_destination_country', $destination_country, $billing_country, $shipping_country, $shop_country );

Parameter	Type	Description
`$destination_country`	string	Calculated destination country (per WooCommerce settings)
`$billing_country`	string	Customer billing country code
`$shipping_country`	string	Customer shipping country code
`$shop_country`	string	Shop country code

Return value: string - Country code for VAT calculation

Example:

/**
 * Always use billing country for B2B
 *
 * @param string $destination Calculated destination country
 * @param string $billing     Billing country
 * @param string $shipping    Shipping country
 * @param string $shop        Shop country
 *
 * @return string Modified destination country
 */
function my_destination_country( string $destination, string $billing, string $shipping, string $shop ): string {
    // For B2B always use billing country
    if ( WC()->customer && WC()->customer->get_meta( 'billing_ic' ) ) {
        return $billing;
    }

    return $destination;
}
add_filter( 'wpify_woo_icdic_destination_country', 'my_destination_country', 10, 4 );

`wpify_woo_icdic_vat_exempt_result`

Overrides VAT exemption decision.

apply_filters( 'wpify_woo_icdic_vat_exempt_result', $result, $billing_country, $shipping_country, $vat_id, $destination_country );

Parameter	Type	Description
`$result`	array	Result: `['exempt' => bool, 'reason' => string]`
`$billing_country`	string	Billing country code
`$shipping_country`	string	Shipping country code
`$vat_id`	string	Customer Tax ID
`$destination_country`	string	Destination country for calculation

Return value: array - ['exempt' => bool, 'reason' => string]

Possible reason values:

domestic - Domestic sale (destination country = shop country)
export - Export to third countries outside EU
reverse_charge - EU Reverse Charge (B2B within EU)
legacy - Exempted via deprecated setting
standard - Standard sale without exemption

Example:

/**
 * Exempt from VAT for specific countries outside EU
 *
 * @param array  $result      Decision result
 * @param string $billing     Billing country
 * @param string $shipping    Shipping country
 * @param string $vat_id      Customer Tax ID
 * @param string $destination Destination country
 *
 * @return array Modified result
 */
function my_vat_exempt_result( array $result, string $billing, string $shipping, string $vat_id, string $destination ): array {
    // Switzerland and Norway - always exempt
    if ( in_array( $destination, array( 'CH', 'NO' ), true ) ) {
        return array(
            'exempt' => true,
            'reason' => 'export',
        );
    }

    return $result;
}
add_filter( 'wpify_woo_icdic_vat_exempt_result', 'my_vat_exempt_result', 10, 5 );

`wpify_woo_icdic_pre_vies_validation`

Bypass VIES validation and return custom result. Called before VIES query.

apply_filters( 'wpify_woo_icdic_pre_vies_validation', $pre_result, $dic );

Parameter	Type	Description
`$pre_result`	bool\|null	`null` = continue with VIES, `true`/`false` = bypass
`$dic`	string	Tax ID to validate (including country prefix)

Return value:

true - Tax ID is valid (bypass VIES)
false - Tax ID is invalid (bypass VIES)
null - Continue with normal VIES validation

Example:

/**
 * Skip VIES for test Tax IDs
 *
 * @param bool|null $pre_result Previous result
 * @param string    $dic        Tax ID to validate
 *
 * @return bool|null Result or null to continue
 */
function my_skip_vies_for_test( $pre_result, string $dic ) {
    // Skip VIES for test Tax IDs
    if ( str_starts_with( $dic, 'TEST' ) ) {
        return true; // Consider as valid
    }

    // Skip VIES during outage - accept based on format
    if ( defined( 'VIES_FALLBACK' ) && VIES_FALLBACK ) {
        if ( preg_match( '/^[A-Z]{2}[0-9A-Z]+$/', $dic ) ) {
            return true;
        }
    }

    return null; // Continue with VIES validation
}
add_filter( 'wpify_woo_icdic_pre_vies_validation', 'my_skip_vies_for_test', 10, 2 );

`wpify_woo_icdic_vies_validation_result`

Modifies VIES validation result after it’s performed.

apply_filters( 'wpify_woo_icdic_vies_validation_result', $is_valid, $dic );

Parameter	Type	Description
`$is_valid`	bool	VIES validation result
`$dic`	string	Tax ID that was validated

Return value: bool - Modified validation result

Example:

/**
 * Log VIES results
 *
 * @param bool   $is_valid Validation result
 * @param string $dic      Validated Tax ID
 *
 * @return bool Unchanged result
 */
function my_log_vies_result( bool $is_valid, string $dic ): bool {
    error_log( sprintf(
        'VIES validation for %s: %s',
        $dic,
        $is_valid ? 'valid' : 'invalid'
    ) );

    return $is_valid;
}
add_filter( 'wpify_woo_icdic_vies_validation_result', 'my_log_vies_result', 10, 2 );

`wpify_woo_add_ic_dic_to_address`

Controls whether Company ID/Tax ID is added to formatted address (emails, customer account).

apply_filters( 'wpify_woo_add_ic_dic_to_address', $add );

Parameter	Type	Description
`$add`	bool	Whether to add Company ID/Tax ID to address (default `true`)

Return value: bool - Whether to add to address

Example:

/**
 * Don't add Company ID/Tax ID to formatted address
 *
 * @param bool $add Whether to add
 *
 * @return bool Modified value
 */
function my_hide_ic_dic_in_address( bool $add ): bool {
    return false;
}
add_filter( 'wpify_woo_add_ic_dic_to_address', 'my_hide_ic_dic_in_address' );

Integration with Invoicing Plugins

Displaying Reverse Charge Note on Invoice

The module does not automatically display notes on invoices. This must be handled by your invoicing plugin based on meta data.

Integration with WPify Woo Fakturoid

If you use the WPify Woo Fakturoid plugin, Reverse Charge and export notes are automatically processed based on meta data from this module.

Custom Invoicing Plugin

Example integration for custom invoicing solution:

/**
 * Add VAT note to invoice
 *
 * @param WC_Order $order Order
 *
 * @return void
 */
function my_invoice_vat_note( WC_Order $order ): void {
    $is_exempt = wc_string_to_bool( $order->get_meta( 'is_vat_exempt' ) );
    $reason = $order->get_meta( '_wpify_vat_exempt_reason' );

    if ( ! $is_exempt ) {
        return;
    }

    $notes = array(
        'reverse_charge' => 'Reverse charge - VAT to be paid by the recipient pursuant to Art. 196 of Directive 2006/112/EC',
        'export'         => 'VAT exempt - supply of goods to third country',
    );

    if ( isset( $notes[ $reason ] ) ) {
        echo '<p class="tax-note">' . esc_html( $notes[ $reason ] ) . '</p>';
    }
}
add_action( 'my_invoice_footer', 'my_invoice_vat_note' );

Integration with WooCommerce PDF Invoices & Packing Slips

/**
 * Add VAT note to WCPDF invoice
 *
 * @param string   $document_type Document type
 * @param WC_Order $order         Order
 *
 * @return void
 */
function my_wcpdf_vat_note( string $document_type, WC_Order $order ): void {
    if ( $document_type !== 'invoice' ) {
        return;
    }

    $is_exempt = wc_string_to_bool( $order->get_meta( 'is_vat_exempt' ) );
    $reason = $order->get_meta( '_wpify_vat_exempt_reason' );

    if ( ! $is_exempt ) {
        return;
    }

    $notes = array(
        'reverse_charge' => __( 'Reverse charge - VAT to be paid by recipient', 'my-plugin' ),
        'export'         => __( 'VAT exempt - export outside EU', 'my-plugin' ),
    );

    if ( isset( $notes[ $reason ] ) ) {
        echo '<tr class="vat-exempt-note"><td colspan="3">' . esc_html( $notes[ $reason ] ) . '</td></tr>';
    }
}
add_action( 'wpo_wcpdf_after_order_data', 'my_wcpdf_vat_note', 10, 2 );

REST API

The module adds REST API endpoint for Company ID and Tax ID validation:

POST /wp-json/wpify-woo/v1/ic-dic/validate

Parameter	Type	Required	Description
`ic`	string	No	Company ID to validate (ARES)
`dic`	string	No	Tax ID to validate (VIES)
`country`	string	Yes	Country code (ISO 3166-1 alpha-2)

Request example:

fetch('/wp-json/wpify-woo/v1/ic-dic/validate', {
    method: 'POST',
    headers: {
        'Content-Type': 'application/json',
    },
    body: JSON.stringify({
        ic: '12345678',
        country: 'CZ'
    })
})
.then(response => response.json())
.then(data => console.log(data));

CSS Classes

Class	Description
`vat-exempt`	Added to order in order list
`wpify-woo-ic-dic__toggle`	”I’m buying as a company” checkbox
`wpify-woo-ic-dic__company_field`	Business fields (hidden when not checked)
`wpify-woo-ic--validate`	Company ID field with ARES validation
`wpify-woo-vies--validate`	Tax ID field with VIES validation

JavaScript Events

// After successful ARES data load
document.addEventListener('wpify_woo_ares_loaded', function(e) {
    console.log('ARES data:', e.detail);
});

// After Tax ID VIES validation
document.addEventListener('wpify_woo_vies_validated', function(e) {
    console.log('VIES result:', e.detail.valid);
});

Where to Place Code

You can place custom functions:

In your child theme’s functions.php
Using the Code Snippets plugin
In a custom plugin