Allow users to make the billing fields optional for the PMPro checkout page when they check a checkbox.

make-billing-fields-optional.php

<?php
/**
 * Make billing fields optional at checkout
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

// Add a checkbox to make billing fields optional
function add_optional_billing_checkbox() {
	if ( ! defined( 'PMPRO_VERSION' ) ) {
		return;
	}

	$level = pmpro_getLevelAtCheckout();
	if ( empty( $level ) || ! empty( $level->initial_payment ) || ! empty( $level->billing_amount ) ) {
		?>
		<div class="pmpro_checkout-field pmpro_checkout-field-optional-billing">
			<label>
				<input type="checkbox" id="optional_billing" name="optional_billing" value="1">
				<?php _e( 'Make billing fields optional', 'paid-memberships-pro' ); ?>
			</label>
		</div>
		<?php
	}
}
add_action( 'pmpro_checkout_boxes', 'add_optional_billing_checkbox' );

// Make billing fields optional when checkbox is checked
function make_billing_fields_optional() {
	if ( ! defined( 'PMPRO_VERSION' ) ) {
		return;
	}

	if ( ! empty( $_REQUEST['optional_billing'] ) ) {
		add_filter( 'pmpro_required_billing_fields', '__return_empty_array' );
	}
}
add_action( 'pmpro_checkout_preheader', 'make_billing_fields_optional' );

// Add JavaScript to handle the checkbox behavior
function optional_billing_js() {
	if ( ! defined( 'PMPRO_VERSION' ) ) {
		return;
	}

	$level = pmpro_getLevelAtCheckout();
	if ( empty( $level ) || ! empty( $level->initial_payment ) || ! empty( $level->billing_amount ) ) {
		?>
		<script>
			jQuery(document).ready(function() {
				// Move the optional billing checkbox to the billing section
				var optionalBillingCheckbox = jQuery('.pmpro_checkout-field-optional-billing');
				var billingFieldsDiv = jQuery('.pmpro_form_fields.pmpro_cols-2').first();
				if (optionalBillingCheckbox.length && billingFieldsDiv.length) {
					optionalBillingCheckbox.insertBefore(billingFieldsDiv);
				}

				// Handle checkbox change event
				jQuery('#optional_billing').change(function() {
					var billingFields = jQuery('#pmpro_billing_address_fields');
					if (jQuery(this).is(':checked')) {
						// Hide required indicators and make fields optional
						billingFields.find('.pmpro_asterisk').hide();
						billingFields.find('input, select').prop('required', false);
					} else {
						// Show required indicators and make fields required
						billingFields.find('.pmpro_asterisk').show();
						billingFields.find('input, select').prop('required', true);
					}
				});
			});
		</script>
		<?php
	}
}
add_action( 'wp_footer', 'optional_billing_js' );