private function validateGovernment($vatNumber)
{
$prefix = strtoupper(substr($vatNumber, 0, 2));
$number = (int) substr($vatNumber, 2, 3);
// Government departments
if ($prefix == 'GD') {
return $number < 500 ? true : false;
}
// Health authorities
if ($prefix == 'HA') {
return $number > 499 ? true : false;
}
return false;
}