diff --git a/src/main/java/org/wise/portal/presentation/web/controllers/tag/UserTagController.java b/src/main/java/org/wise/portal/presentation/web/controllers/tag/UserTagController.java
index ad3d60122..e05cb15cd 100644
--- a/src/main/java/org/wise/portal/presentation/web/controllers/tag/UserTagController.java
+++ b/src/main/java/org/wise/portal/presentation/web/controllers/tag/UserTagController.java
@@ -38,7 +38,11 @@ public class UserTagController {
   protected ResponseEntity<Map<String, Object>> createTag(Authentication auth,
       @RequestBody Map<String, Object> tag) {
     User user = userService.retrieveUserByUsername(auth.getName());
-    UserTag userTag = userTagsService.createTag(user, (String) tag.get("text"));
+    String tagText = ((String) tag.get("text")).trim();
+    if (userTagsService.hasTag(user, tagText)) {
+      return ResponseEntityGenerator.createError("tagAlreadyExists");
+    }
+    UserTag userTag = userTagsService.createTag(user, tagText);
     return ResponseEntityGenerator.createSuccess(userTag.toMap());
   }
 
diff --git a/src/main/java/org/wise/portal/service/usertags/UserTagsService.java b/src/main/java/org/wise/portal/service/usertags/UserTagsService.java
index d78a7ea56..02be2ca7b 100644
--- a/src/main/java/org/wise/portal/service/usertags/UserTagsService.java
+++ b/src/main/java/org/wise/portal/service/usertags/UserTagsService.java
@@ -17,6 +17,8 @@ public interface UserTagsService {
 
   Set<UserTag> getTags(User user, Project project);
 
+  Boolean hasTag(User user, String tag);
+
   Boolean hasTag(User user, Project project, String tag);
 
   void applyTag(Project project, UserTag tag);
diff --git a/src/main/java/org/wise/portal/service/usertags/impl/UserTagsServiceImpl.java b/src/main/java/org/wise/portal/service/usertags/impl/UserTagsServiceImpl.java
index ed99f01b4..5d6219539 100644
--- a/src/main/java/org/wise/portal/service/usertags/impl/UserTagsServiceImpl.java
+++ b/src/main/java/org/wise/portal/service/usertags/impl/UserTagsServiceImpl.java
@@ -57,6 +57,12 @@ public Set<UserTag> getTags(User user, Project project) {
         .collect(Collectors.toSet());
   }
 
+  @Override
+  public Boolean hasTag(User user, String tag) {
+    return getTags(user).stream()
+        .anyMatch(t -> t.getText().toLowerCase().equals(tag.toLowerCase()));
+  }
+
   @Override
   public Boolean hasTag(User user, Project project, String tag) {
     MutableAclTargetObjectIdentity mutableObjectIdentity = getMutableObjectIdentity(project);