diff -u b/src/Form/JobItemForm.php b/src/Form/JobItemForm.php
--- b/src/Form/JobItemForm.php
+++ b/src/Form/JobItemForm.php
@@ -335,26 +335,16 @@
         // Update the translation, this will only update the translation in case
         // it has changed. We have two different cases, the first is for nested
         // texts.
-        if (is_array($value['translation'])) {
-          $data = array(
-            '#text' => $value['translation']['value'],
-            '#origin' => 'local',
-          );
-        }
-        else {
-          $data = array(
-            '#text' => $value['translation'],
-            '#origin' => 'local',
-          );
-        }
-
-        // Unmask the translation's HTML tags.
+        $text = is_array($value['translation']) ? $value['translation']['value'] : $value['translation'];
         $data_item = $item->getData($data_service->ensureArrayKey($key));
-        if (isset($data_item['#translation']['#text'])) {
-          $text = $data_item['#translation']['#text'];
-          \Drupal::moduleHandler()->alter('tmgmt_data_item_text_input', $text, $data_item, $item);
-        }
 
+        // Mask the translation's HTML tags.
+        \Drupal::moduleHandler()->alter('tmgmt_data_item_text_input', $text, $data_item, $item);
+
+        $data = [
+          '#text' => $text,
+          '#origin' => 'local',
+        ];
         if ($data['#text'] == '' && $item->isActive() && $form_state->getTriggeringElement()['#value'] != '✓') {
           $data = NULL;
           continue;
diff -u b/tmgmt_test/tmgmt_test.module b/tmgmt_test/tmgmt_test.module
--- b/tmgmt_test/tmgmt_test.module
+++ b/tmgmt_test/tmgmt_test.module
@@ -48,7 +48,7 @@
 /**
  * Implements hook_tmgmt_data_item_text_output_alter().
  */
-function tmgmt_test_tmgmt_data_item_text_output_alter(&$text, $data_item, JobItemInterface &$job_item) {
+function tmgmt_test_tmgmt_data_item_text_output_alter(&$text, $data_item, JobItemInterface $job_item) {
   $text = str_replace('First', 'Second', $text);
 }
 
only in patch2:
unchanged:
--- a/src/Tests/TMGMTUiReviewTest.php
+++ b/src/Tests/TMGMTUiReviewTest.php
@@ -467,7 +467,7 @@ class TMGMTUiReviewTest extends EntityTestBase {
 
     // Create the node.
     $settings = array(
-      'title' => $this->randomMachineName(),
+      'title' => 'First node',
       'type' => 'test_bundle',
       'body_test' => array(
         $this->randomMachineName(),
@@ -487,7 +487,11 @@ class TMGMTUiReviewTest extends EntityTestBase {
     $job_item->save();
 
     // Access to the review form.
-    $this->drupalGet('admin/tmgmt/items/1');
+    $this->drupalGet('admin/tmgmt/items/'. $job_item->id());
+    // Check that 'hook_tmgmt_data_item_text_output_alter' has been called.
+    $data_item = $job_item->getData();
+    $this->assertEqual($data_item['title'][0]['value']['#text'], 'First node');
+    $this->assertFieldByName('title|0|value[source]', 'Second node');
 
     // Test that all the items are being displayed.
     $this->assertRaw('name="title|0|value[source]"');
@@ -530,6 +534,21 @@ class TMGMTUiReviewTest extends EntityTestBase {
     $this->assertEqual($label[0], 'Alternative text');
     $label = $this->xpath('//*[@id="tmgmt-ui-element-image-test-single-wrapper"]/table/tbody/tr[3]/td[1]/div[1]/label');
     $this->assertEqual($label[0], 'Title');
+
+    // Check 'hook_tmgmt_data_item_text_input_alter' has been called on saving.
+    $this->drupalPostForm(NULL, ['title|0|value[translation]' => 'Second node translation'], 'Save');
+    // Clean the storage and get the updated job item data.
+    \Drupal::entityTypeManager()->getStorage('tmgmt_job_item')->resetCache();
+    $job_item = JobItem::load($job_item->id());
+    $data = $job_item->getData();
+    $this->assertEqual($data_item['title'][0]['value']['#text'], 'First node');
+    $this->assertEqual($data['title'][0]['value']['#translation']['#text'], 'First node translation');
+
+    // Access to the review form.
+    $this->drupalGet('admin/tmgmt/items/'. $job_item->id());
+    // Check that 'hook_tmgmt_data_item_text_output_alter' has been called.
+    $this->assertFieldByName('title|0|value[source]', 'Second node');
+    $this->assertFieldByName('title|0|value[translation]', 'Second node translation');
   }
 
   /**
only in patch2:
unchanged:
--- a/tmgmt.api.php
+++ b/tmgmt.api.php
@@ -6,6 +6,7 @@
  */
 
 use Drupal\tmgmt\JobInterface;
+use Drupal\tmgmt\JobItemInterface;
 
 /**
  * @addtogroup tmgmt_source
@@ -297,3 +298,31 @@ function hook_tmgmt_job_after_request_translation(JobInterface $job) {
     }
   }
 }
+
+/**
+ * Allows to alter a text's segment unmasking the HTML tags from a tmgmt-tag.
+ *
+ * @param string $text
+ *   The text's segment to alter.
+ * @param array $data_item
+ *   The data item.
+ * @param \Drupal\tmgmt\JobItemInterface $job_item
+ *   The job item context.
+ */
+function hook_tmgmt_data_item_text_output_alter(&$text, $data_item, JobItemInterface $job_item) {
+  $text = str_replace('First', 'Second', $text);
+}
+
+/**
+ * Allows to alter a text's segment masking the HTML tags into a tmgmt-tag.
+ *
+ * @param string $text
+ *   The text's segment to alter.
+ * @param array $data_item
+ *   The data item.
+ * @param \Drupal\tmgmt\JobItemInterface $job_item
+ *   The job item context.
+ */
+function hook_tmgmt_data_item_text_input_alter(&$text, $data_item, JobItemInterface $job_item) {
+  $text = str_replace('Second', 'First', $text);
+}