woocommerce_customer_taxable_address filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_customer_taxable_address', 'filter_function_name_1970' );
function filter_function_name_1970( $array ){
	// filter...

	return $array;
}

$array

-

Where the hook is called

return apply_filters( 'woocommerce_customer_taxable_address', array( $country, $state, $postcode, $city ) );

Where in WP core the hook is used WooCommerce