Importing a list of customer groups into Magento from a CSV file.

ImportCustomerGroups.php

<?php

equire_once('app/Mage.php');
umask(0);
Mage::app();
 
$customer = Mage::getModel('customer/customer');
 
$csv = array();
 
// prepare a file called groups.csv with group_name, tax_class_id
 
if( ($handle = fopen('groups.csv', "r")) !== FALSE) {
   $rowCounter = 0;
   while (($rowData = fgetcsv($handle, 0, ",")) !== FALSE) {
       if( 0 === $rowCounter) {
           $headerRecord = $rowData;
       } else {
           foreach( $rowData as $key => $value) {
               $csv[ $rowCounter - 1][ $headerRecord[ $key] ] = $value;  
           }
       }
       $rowCounter++;
   }
   fclose($handle);
}
 
foreach ($csv as $customer) {
  
  $group_data = array();
  $group_data['customer_group_code'] = $customer['group_name'];
  $group_data['tax_class_id'] = $customer['tax_class_id']; // what is the tax_class you want them in
  
  Mage::getSingleton('customer/group')->setData($group_data)->save();
  
}

?>