diff --git a/controllers/timesheet.php b/controllers/timesheet.php
index c292dcb06ea1926e40728a5a25e3384066850139..ed2ce2ebfa949ed9358c352a72f47efc011de581 100644
--- a/controllers/timesheet.php
+++ b/controllers/timesheet.php
@@ -425,7 +425,7 @@ class TimesheetController extends PluginController {
         }
 
         if ($timesheet && $timesheet->sum !== null) {
-            $timesheet->finished = true;
+            $timesheet->finished = 1;
             $timesheet->finished_at = date('Y-m-d');
             $timesheet->store();
             $timesheet->send_finished_mail();
@@ -447,9 +447,9 @@ class TimesheetController extends PluginController {
 
         //sämtliche Bestätigungsvorgänge verlieren Gültgkeit, wenn der Stundenzettel zur Veränderung durch Hilfskraft freigegeben wird
         if ($timesheet) {
-            $timesheet->finished = false;
-            $timesheet->approved = false;
-            $timesheet->complete = false;
+            $timesheet->finished = 0;
+            $timesheet->approved = 0;
+            $timesheet->complete = 0;
             $timesheet->finished_at = null;
             $timesheet->approved_at = null;
             $timesheet->approver_id = null;
@@ -471,7 +471,7 @@ class TimesheetController extends PluginController {
         }
 
         if ($timesheet) {
-            $timesheet->approved = true;
+            $timesheet->approved = 1;
             $timesheet->approved_at = date('Y-m-d');
             $timesheet->approver_id = $GLOBALS['user']->id;
             $timesheet->store();
@@ -481,6 +481,26 @@ class TimesheetController extends PluginController {
         $this->redirect('timesheet/index/'. $timesheet->contract->id);
     }
 
+    public function unapprove_action($timesheet_id)
+    {
+        $timesheet = StundenzettelTimesheet::find($timesheet_id);
+
+        if (!$timesheet->can_approve($GLOBALS['user']->id)) {
+            throw new AccessDeniedException($this->_("Sie haben keine Zugriffsberechtigung"));
+        }
+
+        if ($timesheet) {
+            $timesheet->approved = 0;
+            $timesheet->complete = 0;
+            $timesheet->approved_at = null;
+            $timesheet->approver_id = null;
+            $timesheet->store();
+            PageLayout::postMessage(MessageBox::success($this->_("Bestätigungsvermerk wurde gelöscht.")));
+        }
+
+        $this->redirect('timesheet/index/'. $timesheet->contract->id);
+    }
+
     public function complete_action($timesheet_id)
     {
         $timesheet = StundenzettelTimesheet::find($timesheet_id);
diff --git a/views/timesheet/admin_index.php b/views/timesheet/admin_index.php
index b277e5d8a6b2118a6e61621b146d0f089e7bfc4c..10b16a184c0132bdd8986da1ade37172e0fef70c 100644
--- a/views/timesheet/admin_index.php
+++ b/views/timesheet/admin_index.php
@@ -58,6 +58,10 @@
                                 <? $menu->addLink($controller->url_for('timesheet/approve', $timesheet->id),
                                        $controller->_('Korrektheit der Angaben bestätigen'), Icon::create($status_infos['approved']['icon'])
                                    ) ?>
+                            <? else: ?>
+                                <? $menu->addLink($controller->url_for('timesheet/unapprove', $timesheet->id),
+                                       $controller->_('Bestätigungsvermerk zurückziehen'), Icon::create('refresh')
+                                   ) ?>
                             <? endif ?>
                             <? $menu->addLink($controller->url_for('timesheet/unlock', $timesheet->id),
                                    $controller->_('Einreichen rückgängig machen'), Icon::create('rotate-left'),
diff --git a/views/timesheet/index.php b/views/timesheet/index.php
index a4bf4e0d717e8c8f01c8c53b758cbb4b1e8e9ce4..7b997843f1e910dcfd507c882359f11d2c0db059 100644
--- a/views/timesheet/index.php
+++ b/views/timesheet/index.php
@@ -56,6 +56,10 @@
                                     <? $menu->addLink($controller->url_for('timesheet/approve', $timesheet->id),
                                            $controller->_('Korrektheit der Angaben bestätigen'), Icon::create($status_infos['approved']['icon'])
                                        ) ?>
+                                <? else: ?>
+                                    <? $menu->addLink($controller->url_for('timesheet/unapprove', $timesheet->id),
+                                           $controller->_('Bestätigungsvermerk zurückziehen'), Icon::create('refresh')
+                                       ) ?>
                                 <? endif ?>
                                 <? $menu->addLink($controller->url_for('timesheet/unlock', $timesheet->id),
                                        $controller->_('Einreichen rückgängig machen'), Icon::create('rotate-left'),