diff --git a/Layout/default/TimerecordingBilling/Index.php b/Layout/default/TimerecordingBilling/Index.php
index a1a8f0988..b4f67ceee 100644
--- a/Layout/default/TimerecordingBilling/Index.php
+++ b/Layout/default/TimerecordingBilling/Index.php
@@ -64,7 +64,7 @@
                     }
                     ?>
                     <tr>
-                        <td class="text-center"><a
+                        <td data-order="<?= strtotime("01.".$month) ?>" class="text-center"><a
                                     href="<?= self::getUrl("TimerecordingBilling", "detail", ["month" => $month]) ?>"> <?= $month ?></a>
                         </td>
                         <td class="text-center"><?= $closed ?></td>