How to Extend the EDD Checkout with Custom Fields (eddsellservices.com)

01-snippet.php

// 1. Render
add_action( 'edd_purchase_form_after_personal_info', function () {
 $value = edd_get_option( 'vat_id_placeholder', '' );
 ?>
 <fieldset id="edd_checkout_vat_id">
 <legend><?php esc_html_e( 'VAT ID (optional)', 'mystore' ); ?></legend>
 <p>
 <label class="edd-label" for="edd-vat-id">
 <?php esc_html_e( 'EU VAT Registration Number', 'mystore' ); ?>
 </label>
 <input type="text" class="edd-input" id="edd-vat-id"
 name="edd_vat_id" autocomplete="off" />
 <span class="edd-description">
 <?php esc_html_e( 'B2B customers in EU countries: enter VAT ID to remove VAT from your purchase.', 'mystore' ); ?>
 </span>
 </p>
 </fieldset>
 <?php
} );

// 2. Validate
add_action( 'edd_checkout_error_checks', function ( $valid_data, $post_data ) {
 $vat_id = ! empty( $post_data['edd_vat_id'] ) ? trim( $post_data['edd_vat_id'] ) : '';

 if ( $vat_id && ! preg_match( '/^[A-Z]{2}[0-9A-Z]{2,12}$/', strtoupper( $vat_id ) ) ) {
 edd_set_error( 'invalid_vat_id', __( 'Please enter a valid EU VAT ID (e.g. DE123456789).', 'mystore' ) );
 }
}, 10, 2 );

// 3. Save to order
add_action( 'edd_insert_payment', function ( $payment_id, $payment_data ) {
 if ( ! empty( $_POST['edd_vat_id'] ) ) {
 edd_update_payment_meta(
 $payment_id,
 '_edd_vat_id',
 sanitize_text_field( wp_unslash( $_POST['edd_vat_id'] ) )
 );
 }
}, 10, 2 );

02-snippet.php

add_action( 'edd_purchase_form_after_personal_info', function () {
 $cart_items = edd_get_cart_contents();
 $needs_team_size = false;

 foreach ( $cart_items as $item ) {
 if ( get_post_meta( $item['id'], '_edd_is_team_license', true ) ) {
 $needs_team_size = true;
 break;
 }
 }

 if ( ! $needs_team_size ) {
 return;
 }
 ?>
 <fieldset>
 <legend><?php esc_html_e( 'Team Details', 'mystore' ); ?></legend>
 <p>
 <label for="edd-team-size"><?php esc_html_e( 'Number of seats', 'mystore' ); ?></label>
 <input type="number" min="1" max="500" name="edd_team_size"
 id="edd-team-size" class="edd-input" required />
 </p>
 </fieldset>
 <?php
} );

03-snippet.js

(function ( $ ) {
 $( document ).ready( function () {
 const businessToggle = $( '#edd-is-business' );
 const vatFieldset = $( '#edd-vat-fieldset' );

 vatFieldset.hide();

 businessToggle.on( 'change', function () {
 if ( this.checked ) {
 vatFieldset.show();
 $( '#edd-vat-id' ).attr( 'required', true );
 } else {
 vatFieldset.hide();
 $( '#edd-vat-id' ).removeAttr( 'required' ).val( '' );
 }
 } );
 } );
} )( jQuery );

04-snippet.php

add_action( 'edd_view_order_details_payment_meta_after', function ( $payment_id ) {
 $vat_id = edd_get_payment_meta( $payment_id, '_edd_vat_id' );
 $team_size = edd_get_payment_meta( $payment_id, '_edd_team_size' );

 if ( ! $vat_id && ! $team_size ) {
 return;
 }
 ?>
 <div class="edd-order-custom-fields">
 <h3><?php esc_html_e( 'Custom Fields', 'mystore' ); ?></h3>
 <?php if ( $vat_id ) : ?>
 <p><strong>VAT ID:</strong> <?php echo esc_html( $vat_id ); ?></p>
 <?php endif; ?>
 <?php if ( $team_size ) : ?>
 <p><strong>Team Size:</strong> <?php echo esc_html( $team_size ); ?></p>
 <?php endif; ?>
 </div>
 <?php
} );

05-snippet.js

add_filter( 'edd_cart_tax', function ( $tax, $subtotal ) {
 if ( ! empty( $_POST['edd_vat_id'] ) && is_eu_customer() ) {
 // B2B reverse-charge, VAT is the buyer's responsibility.
 return 0;
 }
 return $tax;
}, 10, 2 );

06-snippet.js

add_filter( 'edd_cart_item_price', function ( $price, $item ) {
 if ( isset( $_POST['edd_team_size'] ) && (int) $_POST['edd_team_size'] > 1 ) {
 $seats = (int) $_POST['edd_team_size'];
 return $price * $seats;
 }
 return $price;
}, 10, 2 );

07-snippet.php

add_action( 'edd_subscription_post_create', function ( $subscription_id, $subscription ) {
 $payment_id = $subscription->parent_payment_id;
 $vat_id = edd_get_payment_meta( $payment_id, '_edd_vat_id' );
 if ( $vat_id ) {
 update_post_meta( $subscription_id, '_vat_id', $vat_id );
 }
}, 10, 2 );