woocommerce change VAT to GST

inside wp-content/themes/SELECTED_THEME/functions.php add below code

add_filter( 'gettext', function( $translation, $text, $domain ) {
	if ( $domain == 'woocommerce' ) {
		if ( $text == 'VAT' ) { $translation = 'GST'; }
	}
	return $translation;
}, 10, 3 );


######## Reason ############

What’s showing as the text, depends on your site’s language (not necessarily
your location), so if you have it set to English, it will indeed show 
“(ex. VAT)”.

You can change this by using a translation plugin such as Loco Translate and 
“translate” the string (ex. VAT) to something else, like (ex. GST).