This snippet is made for the EU VAT for Gravity Forms. It can apply the tax rate of the default country to all other EU countries.

default_to_base_country_vat.php

<?php 

/**
 * Snippet to apply the tax rate of the base country to ALL EU countries
 * 
 * @param Int $rate  
 * @param string $country_code  the 2 digit ISO code of the country * 
 * @return Int $rate
 * @version 1.0
 * @link https://geekontheroad.com/eu-vat-for-gravity-forms/
 * @author Johan dhollander
 *
 *
 * INSTRUCTIONS
 * 1. Copy this whole snippet excluding the beginning <?php tag
 * 2. Change the " 1 " in the below line to your form ID or remove " _1 " to apply to all forms
 **/
add_filter("gotreu_standard_vat_rate_1" , "gotreu_default_to_base_country_vat", 10,2);

function gotreu_default_to_base_country_vat( $rate , $country_code) {
    $class = gotrgf_euvat_addon();
    $settings = $class->get_plugin_settings();
    $base_country = $settings["eu_vat_default_country"];   
    $explode = explode(":",$base_country);
    $rate = intval($explode[1]);     
    return $rate;
}