Change the position of the EU VAT Number field on the Checkout page
remove_action( 'woocommerce_after_checkout_billing_form', array( 'WC_EU_VAT_Number', 'vat_number_field' ) );
add_action( 'HOOK-YOU-WANT-TO-ADD-IT-TO', array( 'WC_EU_VAT_Number', 'vat_number_field' ) );