diff --git a/CRM/Contact/Form/Edit/TagsAndGroups.php b/CRM/Contact/Form/Edit/TagsAndGroups.php
index e9ffa6f6677b..611f2751cf5e 100644
--- a/CRM/Contact/Form/Edit/TagsAndGroups.php
+++ b/CRM/Contact/Form/Edit/TagsAndGroups.php
@@ -137,6 +137,9 @@ public static function buildQuickForm(
 
       if (!empty($tags)) {
         $form->add('select2', 'tag', ts('Tag(s)'), $tags, FALSE, ['class' => 'huge', 'placeholder' => ts('- select -'), 'multiple' => TRUE]);
+        if ($isRequired) {
+          $form->addRule('tag', ts('Tag is a required field.'), 'required');
+        }
       }
 
       // build tag widget