in Magento

Get Child Categories in Magento using getChildCategories()

ini_set('display_errors', '1');
error_reporting(E_ALL);

// include magento goodies
require '../app/Mage.php';

Mage::app();

//$currentCategory = Mage::registry('current_category');

$id = 4; //  represents the current category id for my test

$currentCategory = Mage::getModel('catalog/category')->load($id);

$helper = Mage::helper('catalog/category');

if( is_null( $currentCategory ) ) {
	echo '$currentCategory is null';
} else {

	// LEVEL 1
	echo $currentCategory->getName() . '<br>' . PHP_EOL;

	$level_1_children = $currentCategory->getChildrenCategories();

	foreach ( $level_1_children as $level_2 ) {
		// LEVEL 2
			echo '-' . $level_2->getName() . '<br>' . PHP_EOL;
			$level_2_children = $level_2->getChildrenCategories();
			foreach ( $level_2_children as $level_3 ) {
				// LEVEL 3
				$level_3->load();
				if( $level_3->getIncludeInMenu() ) {
					echo '--' . $level_3->getName() . '<br>' . PHP_EOL;
				} else {
					echo '--<span style="color:magenta">' . $level_3->getName() . '</span><br>' . PHP_EOL;
				}
			}
	}
}