<?php

$tags = Input::get('tag');
$tags = explode(",", $tags);

foreach($tags as $key => $tag):
    $tag->slug = $tag;

    if($tag->save()): 
        $tagId = $tag->id;                                
        $listag = new ListTag;
        $listag->list_id = $listId;
        $listag->tag_id = $tagId;
        $listag->save();
    endif;

endforeach;