Adding Custom Checkout Fields

Adding Custom Checkout Fields — a practical guide to WooCommerce custom checkout fields with clear examples you can reuse in real projects.

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Short description

For block checkout, also implement Blocks field extensibility. Start with classic fields, then add block support.

Add checkout field

add_filter('woocommerce_checkout_fields', function ($fields) {
    $fields['billing']['billing_gstin'] = [
        'label' => 'GSTIN',
        'required' => false,
        'class' => ['form-row-wide'],
        'priority' => 120,
    ];
    return $fields;
});