diff -r b5474c68c433 -r 0987c3565751 vendor/plugins/redmine_tags/assets/javascripts/tags_input.js
--- a/vendor/plugins/redmine_tags/assets/javascripts/tags_input.js
+++ b/vendor/plugins/redmine_tags/assets/javascripts/tags_input.js
@@ -86,7 +86,7 @@
   addTagsList: function(tags_list) {
     var tags = tags_list.split(',');
     for (var i = 0; i < tags.length; i++) {
-      this.addTag(tags[i].strip());
+      this.addTag(tags[i].strip().toLowerCase());
     }
   },
 
diff -r b5474c68c433 -r 0987c3565751 vendor/plugins/redmine_tags/lib/redmine_tags/patches/projects_controller_patch.rb
--- a/vendor/plugins/redmine_tags/lib/redmine_tags/patches/projects_controller_patch.rb
+++ b/vendor/plugins/redmine_tags/lib/redmine_tags/patches/projects_controller_patch.rb
@@ -23,8 +23,8 @@
         def add_tags_to_project
 
           if params && params[:project] && !params[:project][:tag_list].nil?
-            old_tags = @project.tag_list.to_s
-            new_tags = params[:project][:tag_list].to_s
+            old_tags = @project.tag_list.to_s.downcase
+            new_tags = params[:project][:tag_list].to_s.downcase
 
             unless (old_tags == new_tags)
               @project.tag_list = new_tags