diff --git a/main/survey/create_new_survey.php b/main/survey/create_new_survey.php
index 575f24ba8b..fab4d3c658 100755
--- a/main/survey/create_new_survey.php
+++ b/main/survey/create_new_survey.php
@@ -74,9 +74,13 @@ if ($action == 'edit' && isset($survey_id) && is_numeric($survey_id)) {
 
     if ($allowSurveyAvailabilityDatetime) {
         $defaults['avail_from'] = api_get_local_time($defaults['avail_from']);
-        $defaults['avail_till'] = api_get_local_time($defaults['avail_till']);
+
+        if (!empty($defaults['avail_till'])) {
+            $defaults['avail_till'] = api_get_local_time($defaults['avail_till']);
+        } else {
+            $defaults['end_date'] = null;
+        }
         $defaults['start_date'] = $defaults['avail_from'];
-        $defaults['end_date'] = $defaults['avail_till'];
     }
 
     $link_info = GradebookUtils::isResourceInCourseGradebook(
@@ -176,7 +180,6 @@ if ($allowSurveyAvailabilityDatetime) {
 }
 
 $form->setRequired($startDateElement);
-$form->setRequired($endDateElement);
 
 $form->addElement('checkbox', 'anonymous', null, get_lang('Anonymous'));
 $visibleResults = [
@@ -344,12 +347,15 @@ if ($action == 'add') {
 $form->addRule('survey_title', get_lang('ThisFieldIsRequired'), 'required');
 $form->addRule('start_date', get_lang('InvalidDate'), $allowSurveyAvailabilityDatetime ? 'datetime' : 'date');
 $form->addRule('end_date', get_lang('InvalidDate'), $allowSurveyAvailabilityDatetime ? 'datetime' : 'date');
-$form->addRule(
-    ['start_date', 'end_date'],
-    get_lang('StartDateShouldBeBeforeEndDate'),
-    'date_compare',
-    'lte'
-);
+
+if (!empty($endDateElement->getCleanValue())) {
+    $form->addRule(
+        ['start_date', 'end_date'],
+        get_lang('StartDateShouldBeBeforeEndDate'),
+        'date_compare',
+        'lte'
+    );
+}
 
 // Setting the default values
 $form->setDefaults($defaults);
diff --git a/main/survey/survey.lib.php b/main/survey/survey.lib.php
index 344a61e41e..084441ad37 100755
--- a/main/survey/survey.lib.php
+++ b/main/survey/survey.lib.php
@@ -465,6 +465,14 @@ class SurveyManager
                 $extraParams['form_fields'] = '';
             }
 
+            if (!empty($values['end_date'])) {
+                $availTill = $allowSurveyAvailabilityDatetime
+                    ? api_get_utc_datetime($values['end_date'].':59')
+                    : $values['end_date'];
+            } else {
+                $availTill = null;
+            }
+
             $params = [
                 'title' => $values['survey_title'],
                 'subtitle' => $values['survey_subtitle'],
@@ -473,9 +481,7 @@ class SurveyManager
                 'avail_from' => $allowSurveyAvailabilityDatetime
                     ? api_get_utc_datetime($values['start_date'].':00')
                     : $values['start_date'],
-                'avail_till' => $allowSurveyAvailabilityDatetime
-                    ? api_get_utc_datetime($values['end_date'].':59')
-                    : $values['end_date'],
+                'avail_till' => $availTill,
                 'is_shared' => $shared_survey_id,
                 'template' => 'template',
                 'intro' => $values['survey_introduction'],
diff --git a/main/survey/surveyUtil.class.php b/main/survey/surveyUtil.class.php
index fe5d7a3248..6e16e90b08 100755
--- a/main/survey/surveyUtil.class.php
+++ b/main/survey/surveyUtil.class.php
@@ -4009,7 +4009,8 @@ class SurveyUtil
 				WHERE
                     survey_invitation.user = $user_id AND
                     survey.avail_from <= '$filterDate' AND
-                    survey.avail_till >= '$filterDate' AND
+                    (survey.avail_till >= '$filterDate' OR
+                    survey.avail_till IS NULL) AND
                     survey.c_id = $course_id AND
                     survey_invitation.c_id = $course_id $sessionCondition
 				";