set_vat_exempt_for_customer_20201104.php

<?php // do not copy this line

add_action( 'woocommerce_checkout_update_order_review', 'set_vat_exempt_for_customer_20201104', 10 );
function set_vat_exempt_for_customer_20201104( $post_data ) {

	if ( isset( $_POST['country'] ) 
		 && isset( $_POST['state'] )
		 && 'ES' === $_POST['country'] 
		 && 'TF' === $_POST['state'] ) {

		WC()->customer->set_props(
			array(
				'is_vat_exempt' => true,
			)
		);
	}
}